CAS CC Tutorial: Making Glowing-Edge CAS CC - Body Parts and CAS Objects

Through curiosity and looking at Valhallansim's Bloodtotem Horns from 2017 in Blender, and a little help from a friend, in looking at the mesh I realised - did I just figure out how to make the glowing body parts and CAS objects? And eventually I did. It took me like 6 hours, but...!

I tried to figure out through some trial and error and many fuck-ups how to make glowing-edged body parts and then CAS items as well. At first I thought Valhallan had extruded the 'edges' of the mesh and made them glow and made it SimGlass for transparent edges, but that's not it. It's a lot easier actually how that edge glow works! So now I'm going to teach you what I learned to the best of my ability.

You've seen this style here with Valhallansim's Bloodtotem horns and also Zynoox's Tian Horns on CAS objects. You may also remember in 2024 Strangegrapefruit made the cool glowing hands and arms that were popular. Thank you to anon friend who helped me as I was figuring out how these horns worked.

This will also explain a bit about the Emission layer, which is an optional step if you want it to actually glow with light in-game. I still explain most of the Blender steps in detail though.

UPDATE 20/04/2026: Completely re-wrote the tutorial.
UPDATE 24/04/2026: A friend discovered a trick that takes out a whole step in this tutorial! That doing Remove Doubles (Merge by Distance in newere versions of Blender) before Fattening the mesh means it doesn't split.
UPDATE 12/05/26: Explains the quick way to make different colours for the glowing CAS content in Sims 4 Studio since you can't use swatches for the Emission layer. Also adds an extra troubleshooting step relevant to an Ask I got and an issue I met myself, where the Additional Texture Space is different to the assumed texture space of a piece of custom content.

UPDATE: 29/09/26: I tried out a trick that surely-sims mentioned. You know I mention how, if you have different-colour Emission maps, you need separate .packages and they will come up separately in CAS? If you give them all the same Prototype ID, they will all be grouped together, and will all still have the different-coloured Emission maps. This is explained 

  

YOU WILL NEED:
- Blender (I use 2.79)
- CAS Tools program
- GIMP (Version 3 series of any sort, since IIRC it has native .dds file support)
(If you already know how to use Photoshop, you can use Photoshop instead for all of the GIMP steps.)
- Sims 4 Studio
- Some patience
- UV Maps for all ages (Download the DropBox links, NOT the preview, the preview is the wrong size)
- UV templates for all ages  (Download the .zip file)

I recommend this tutorial to people who have used Blender, GIMP and Sims 4 Studio to some extent before, but I try to explain everything in detail. Some of it may be way too obvious, but that's necessary for a tutorial. One man's obvious is another man's 'what are you on about?'. 

There are numerous reminders to Save your .blend file throughout. Save frequently, and I recommend saving SEPARATE .blend files after each step so you can easily backtrack if you make a mistake.

There are quite a few large .gif files in this tutorial, so it might be a bit slow if your Internet is slow.

 

Making glowing body parts

We're going to start with making glowing body parts, using the hands as an example. 

Preparing the .package file and mesh  

1. Open Sims 4 Studio. Go to CAS > Create 3D Mesh.

 

 

 2. There's some drop-down categories at the top.

- Select the age category you want to make glowing body parts for to begin with. (Adult for me)
- Select the part category. (I went with Ring Finger (Left) since we just need something with a mesh really, but we're going to change the category later.)
- Make sure Game Pack is set to 'Base Game' (I forgot to do that) so you can be absolutely sure your custom content will be basegame compatible.

- Now save the .package file.

3. With the .package file open in Sims 4 Studio, go to the Meshes tab and export the LOD 0 mesh.

Then open the newly-downloaded file in Blender.

 

Blender Shenanigans

My least favourite part...

4. Open the mesh in Blender.

 

If you do not have a Numpad on your keyboard, go to File > User Preferences on the top menu bar and then enable 'Emulate Numpad', which will make your normal number keys function the same way the Numpad does in Blender. You will need the Numpad to help move the viewpoint around with ease.
- When you open User References, you'll find the option under the 'Input' tab.

 

Make sure this box is ticked.

 

Click 5 on the Numpad on your keyboard, or go to the View menu > View Persp/Ortho and make sure you're in Orthographic Mode (the one that looks flatter) and. if need be, use the 7,9,3 and 1 keys on the keyboard Numpad until you are looking straight ahead at the Sim mesh from the front.
The location of the View menu is shown below.

 

You should be looking at the Sim head-on, with no perspective applied to the model, like below: 

 

I've added labels to make a few things clearer:

 

- IMAGE EDITOR: This section is used mainly to edit and look at the UV map, but you can also import images like textures to layer underneath the UV map. This is useful for making sure your mesh does not overlap the UV space of other CAS items to prevent any 'bleeding' of your object's texture onto other CAS parts. You'll be looking at this later.

 

- 3D VIEW - your workspace with the model and other elements like lamps in it. 

- OUTLINER - This displays all of the current elements in your 3d workspace including lamps, armatures (like the rig you move around to make poses) and all the 3d meshes.

 

- PROPERTIES - There are a lot of options here, but we'll be using a few things from this box during the tutorial. 

- Click the + sign next to the rig in the Outliner box and select the mesh called 'top'.

 

 

If you look across to the right from 'top', ignoring the upside-down triangle, wrench and dots, you'll see more icons. Ignore the camera icon.
- EYE ICON: Controls whether or not the mesh is visible.
- CURSOR ICON: Controls whether or not the mesh is selectable.

 

Make sure that the 'top' mesh's cursor is lit up, so that we can select it. 

 

 

 

5. Press Tab to go into Edit Mode.

 

In Edit Mode, whether or not the mesh (or part of the mesh) is selected will depend on the colour.

 

- In most Blender themes you can choose from, the selected colour is Orange. In the theme I use, Back 2 Black, the de-selected colour is Blue

This will depend on your theme, but you can see if the mesh is selected by clicking S. If the mesh doesn't get bigger or smaller, then it isn't selected. If it is selected, it will grow bigger or smaller depending on which way you move your mouse.

 

In Edit Mode, the A key is the key that selects or de-selects the entire mesh. 

 

If you look at the image below, you'll see a small icon on the bar near the bottom of the screen.
The two squares with the dots on the corner is the 'Limit Selection to Visible' icon, which seems to be highlighted by default.
This means that, if you select parts of the mesh, it will only select the parts that you can see - which is not going to be good, since we want to remove the WHOLE torso part.
Click it so it's not highlighted.

 

You will notice the triangles on the mesh change a little bit when you de-select this option, you will see some faded lines. This is because the triangles of the back of the mesh are now visible too, which is what we want! So let's delete the torso.

 

Whilst you are still in Edit Mode:

 

- Press the A key until the entire Torso, including the arms and hands, is selected.
- Click the Shift + D keys together. This will duplicate the entire mesh. DO NOT move your mouse after, immediately hit the ESC key whilst you do this!
- Don't de-select the duplicated mesh!

 

Now we are going to turn this duplicated mesh into its own separate mesh for the Outlier box:

 

- With your cursor somewhere within the 3d view, click the P key and a small menu called 'Separate' will come up.
From the small drop-down menu that appears, click 'Selection'. 

 

In the Outliner, you'll see a new mesh has appeared under the 'top' mesh called 'top.001'. (You can rename this to 'Glow Mesh' or something if you want. I'll be referring to my glow mesh as the 'top.001' mesh.)

 

We need to move this away from its connection to the rig.
- Click the upside-down orange triangle next to 'top.001'.
Keep your mouse held down and drag it so it is underneath the mesh called 's4studio_mesh_1'.
You'll know you're doing it right if, when you're dragging it downwards, it says 'Drop to Clear Parent' on top of it as you're dragging it.

 

Your Outliner should appear like the above screenshot. Make sure the cursor icon on the same line as 'top.001' is highlighted, so that it is selectable.

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case.  

 

This top.001 mesh is going to be the one that we're editing. 

 

The s4studio_mesh_1 is the ring mesh that we exported, but we'll deal with that later.

 

Press Tab to come out of Edit Mode. 

 

This little menu at the bottom, you can also click this to change from Object Mode (which is what you go back into when you exit Edit More) or you can click it to go into Edit Mode too. It's just easier to click Tab to go in and out, but thought I'd highlight the option so you can look at it to check you're in the correct Mode.

 

The checkered ball icon to the right of this controls the view of the model. Its current setting is Texture, but we will need to temporarily change it later. 

 

 

 

6. We need to make sure the glow will look good in Blender, so we're going to change the Material for the new 'top.001' mesh so it's a vibrant colour.
This will make sense a bit later.

 

So now we go to the Properties menu, which is the box underneath the Outliner.
In the above screenshot, I have highlighted the Material icon (labelled as '1'.)

 

- Click the Minus icon labelled above as '2' and it will delete the body texture from the top.001 mesh. It will turn white. That's what we want, so don't worry!
You can leave it as white if you want, but I suggest picking a colour that's easy to see.

 

We need to make a new material which is just one colour. 
I suggest picking the colour you want for the outside glow, BUT don't worry too much, because it won't affect the colour of the glow of the final product. This is just so we can visualise what it might look like in-game.

 

The above screenshot explains how to make a new material.
Once you have picked a bright, vibrant colour, the top.001 mesh will change to that colour.

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case. 

 

 

 

7. Now we are going to delete the torso.

 

- Double-check that 'Limit Selection to Visible' is OFF as explained earlier in the tutorial.
- Tab to go into Edit Mode. 
- Click A until the mesh is de-selected (on the Back 2 Black Blender theme, the deselected mesh is blue.)

 

So this mesh is made up of:
- Faces (the actual visible parts)
- Edges (the lines)
- and Vertices (the dots). So:

 

- Right-click one of the vertices (the dots). It should turn orange. 
- Now press the L key. You'll notice that a larger part of the torso got selected, but not all of it. 
L selects parts that are linked to your inditial selection.
The likelihood is it selected the front of your mesh, but not the back.
And if it did select the back, it likely only selected one half of the back.

- Hover over the LEFT side of the torso and press L again.
- Hover over the RIGHT side of the torso and press L again. 
- Keep hovering and clicking L on the Torso until the entire Torso's lines are orange.

It should now all be selected. Then:
- click the Delete key. In the menu that comes up, select Faces. Then the coloured top.001 torso should be deleted. The .gif below shows the process:

 

You'll notice in this gif of the above process, mine happened the opposite way - selected the right back, left back and THEN the front of the torso.

 

Now we're going to delete one of the arms using the same method (since we're going to edit the other arm and then mirror it later).
The process is pretty similar to the above. It doesn't matter which arm gets deleted.

 

- Make sure the mesh is de-selected. 
- Right-click a vertex on one of the arms and click L.
- Hover over the hand, forearm and just below the shoulder and click L to make sure the WHOLE mesh is selected.
- Click the Delete key, then select Faces.

 

For our edge glow, we likely don't want it to be all the way up the arm (since I tried this and it looks a bit odd with some of my action poses, but they'd probably look alright for lookbook-type pose pictures)

so we're going to cut off the un-needed part of this mesh.
This also saves on poly count!

 

- Have your cursor at the top of the arm mesh.
- Using the B key, it will turn your cursor into a draggable selection box.
Drag from the top of the arm mesh all the way down to just below the elbow area.
- Click the Delete key and then select Faces again.

 

Don't worry too much if it looks jagged, we can use Edit Mode to delete any stray faces so that the top part doesn't have any any spiky triangles on it.

 

Click the highlighted icon on the bottom bar in Edit Mode and that allows you to select Faces.
Then you can select stray Faces and click Delete and then Faces to remove them. I got rid of this leftover triangle to make the mesh uniform. 

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case.  

8. Now we're going to flip the normals on the arm.
Essentially, what flipping normals does is turn the faces 'inside out', so to say. It's the texture on the surface of the mesh.
When you flip them, the texture is then only visible inside of the mesh. (Thank you to friend for helping me describe this.)

 

(You see that the torso is still there in the above, that's because I forgot to delete the torso when I was taking the picture for this screenshot. Ignore that, I made an error and almost missed a step!).

 

First off, with the top.001 mesh selected, make sure you are still in Edit Mode and the mesh comes up highlighted in triangles.
If it isn't highlighted, press the A key until it is highlighted.

 

- On the Menu bar on the bottom, navigating the drop-down (go-up?) menu.
- Hover over 'Normals' and then on the little pop-out menu, select 'Flip Normals'.

 

You will see that the mesh is now invisible. It's because the coloured faces are now on the INSIDE of the mesh.

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case.  

 

8. Now we are going to resize this mesh to create our edge glow. Make sure you are STILL in Edit Mode!

 

We're going to need the Transform menu.
If you made the 3d view bigger, we may need to pull this menu back out.
On the left side, near the little dragging bar on the transform menu, hover your cursor over it until the cursor turns into two connected left-right arrows and then drag the many out so you can read all the options clearly. 

 

We're going to Fatten the mesh. This will create a sort of 'glow shell' mesh.

 

FIRST OFF! 

 - Make sure you are in Edit Mode with the normal-flipped arm mesh selected. 
- Go to the Mesh manu on the bottom that we used to Flip Normals. 
- This time, go to Mesh > Clean Up > Remove Doubles (or Merge by Distance in later Blender versions). This will prevent the mesh from splitting as you use the Fatten morph on it. (Thank you to friend for discovering this!)
- Click the Shrink / Fatten option.
- Pull in the direction that makes a glow appear around the fingers and then click Enter when you're happy.

- If the mesh 'explodes' and looks shattered, you're pulling in the Shrink direction and not the Fatten direction.

 

SAVE CHECKPOINT: Save the .blend file! Save a separate file this time.

 

Now, highlight the entire mesh in Edit Mode.

 

And now to mirror the mesh.

 

10. Look below at the screenshot.

 

- On the Properties menu box, click the Wrench (labelled above as 1) 
- then click the Add Modifier button (labelled as 2) and select Mirror.
Then the hand mesh will mirror itself onto the other side.
- Click the 'Apply' button that is near the bottom of the Modifier menu, the button left of 'copy'. This will apply the modifier to the mesh itself.

 

SAVE CHECKPOINT: Save the .blend file!

 

 

11. Now we need to merge it with the s4studio mesh. 
Follow the below instructions:

 

- Select the s4studio_mesh_1 mesh in the Outliner.
- Tab into Edit Mode.
- Press A until the s4studio mesh is selected, highlighted orange.
- Tab OUT of Edit Mode.

 

- Select the top.001 mesh in the Outliner.
- Tab into Edit Mode.
- Press A until the hand-glow mesh IS NOT selected.
- Tab OUT of Edit Mode.

 

- In the Outliner box, select the top.001 mesh first.
- Press Shift and the Left Mouse Button at the same time on the s4studio_mesh_1 mesh. 
- Move your cursor into the 3d view and press CTRL + J. 
- If you did it right, you will be left with ONLY the s4studio_mesh_1.

 

- Tab into Edit Mode. If you did it right, then the hand glow mesh will be DESELECTED and the ring SELECTED in orange.
- Press Delete key and then Faces in the little menu that appears and the ring is deleted. 

 

Final step for this mesh: Make sure every mesh under 'rig' (bottom, feet, head, head+2, teeth, top) is made non-selectable again. (IDK if this is necessary, but I always do it just in case since I had issues with importing meshes once due to that I believe (?).)

 

We're done with Blender shenanigans! For now. Thank fuck for that. 

 

SAVE CHECKPOINT: Save the .blend file! Save a separate file this time and save it as something called 'FINAL' or something like that.

Importing the Mesh + Texture 

11. Open your .package file in Sims 4 Studio.
- In the Meshes tab, with LOD 0 selected on the dropdown, click Import Mesh and import the final .blend file for the hands.
- Do the same with LOD 1. I would say don't worry about LOD 2 or LOD 3 for this, but import the mesh into LOD 1 and LOD 0.

 

It won't come up properly yet. We need to sort out the texture and Emission map. We'll start with the regular texture. But, we're going to throw in an extra step to help us stay within the lines. We're going to use gloves texture as a sort of 'stencil' so we can be sure we won't override the wrong texture space.

 

 This is the UV template for a Young Adult Female Sim. As you can see the space is divided up with specific spaces on the texture for specific CC pieces. Bleed over into the wrong part and you risk texture clashes with other CC. For example, if you made a Ring and put the texture in the space where Hats should be, it would mess with most hats your Sim could wear.

 

- UV Maps for all ages and download the UV map you need.
Then we go back into the main menu of Sims 4 Studio. 
(MAKE SURE YOU DOWNLOAD THE 1024 x 2048 ONE, not the HQ one! And make sure you download from the Dropbox links, not the preview, because the preview is the wrong size.)

 

12. In the Main Menu of Sims 4 Studio:

 

- Click the CAS button, it doesn't matter if CAS Standalone or Create 3d Mesh is selected
- For the category, select Gloves. Since I am making these hands for a female Sim, I will be using the yfAcc_GlovesSophisticate_yellow.
- Save the .package file.
- In the Textures tab, export the Diffuse layer.

 

Now, open GIMP. 
(If you are used to Photoshop, then you can do all of the GIMP-related steps in Photoshop but GIMP is my go-to.)

 

- First off, open the UV map of the Skin. 

 

- Go to the menu at the top and click Image. In the dropdown, click Scale Image. If it is 1024 x 2048, wicked. If not, then change either Width to 1024 or Height to 2048 and the other will change automatically. Then click Scale.

 

 

- Then, open the gloves texture file. Press CTRL + A to Select All, and CTRL + X the gloves texture to Cut it. Press Shift + CTRL + A to deselect all.
- Go back to the skin UV, and press CTRL + V to paste the gloves texture on top as a new layer.

 

Now we're going to use the gloves to create a Layer Mask - a digital stencil.

 

13. Click the U key to switch to the Fuzzy Select Tool.

 

Make sure that 'Feather edges' and 'Sample Merged' are UNTICKED!

 

With the Gloves layer being the active, selected layer, Drag your cursor all the way on the gloves until the entire texture is selected with the animated dots around it.

 

- Go to Layer on the top menu. On the dropdown, go to Masks - Add Layer Masks. 
- On the box that comes up called 'Add a Mask to the Layer' (Be sure you're adding it to the Gloves layer), check the 'selection' option then click Add.

 

On the bottom of GIMP on the right should be your Layers. If not, click CTRL + L to bring them up.

 

The LAYER MASK is the black and white template on the right. The actual LAYER is the white-highlighted one on the left. Make sure that you are editing your layer, not your layer mask!

 

Now we colour the hands. (It doesn't matter what colour glow you picked in Blender since it won't transfer to Sims 4 Studio), so pick a strong, bright colour. I'm going with red.

 

14. Make sure you are on your Gloves layer. 
- Select All with CTRL + A, then press Delete and then CTRL + Shift + A to deselect.
- Press the A key for the Airbrush tool.

 

Make sure you pick a low Hardness brush for this, I went with 025.
Now you need to draw the glow texture. I have started off opaque on the hands, with a graduation into transparency a little further up the arm. Remember not to draw any texture that's bigger than your mesh.

 

Notice how as you draw, it stays within the confines of the gloves texture. I love layer masks.
If you want, you can alter the Opacity of the layer (the bar underneath 'mode' on the top of the Layers box) so it looks more faded in-game.

 

If you want the glow to look a bit more smooth and graduated, Shift + U keys bring up the Blur tool which can help with that.

 

When you're happy, delete the Skin layer so you only have the coloured glow and then transparency, and then, on the top menu, go to File > Export As...and export it as a .png. 
A box will come up labelled 'Export as PNG' - don't edit any of the settings and just click Export. 

 

15. Go back to Sims 4 Studio, and open the glowing hands .package file. 
- Under the Textures tab, import the glowing texture into the Diffuse. 

Huzzah! The hands are now red.

(You don't need to do this step if you just want to have the bright red edge-glow. You'll still need this texture for that bright red edge-glow though. If you only want the bright red edge-glow with no colouring on the hands, then import a transparent 1024 x 2048 .png into the Diffuse texture.)

As for the textures:

 

DIFFUSE: This is the glow texture.
SHADOW, SPECULAR, NORMAL, EMISSION : Highlight it and click the Make Blank button (if the button is greyed out then it's already blank)
COLOUR SHIFT MASK, SHEEN - ignore these.

 

Next we have to change the category from Ring to something else, this helps it clash less with more common CAS item slots like rings.

 

Go to the Categories tab. 

 

 

- Set Outfit Type to one of the lesser-used skin details. I am using Skin Detail, Mole (Left Lip). Click 'Apply to All Swatches' to be on the safe side, we only have one swatch but I like to be sure, haha.

 

- Scroll down to 'Part Flags'. Untick Allow for Random and tick Restrict Opposite Frame since from my testing, the fem frame glowing hands don't work on masc frame sims.

 

16. Now we have to change one thing in the Warehouse tab.  

 

- Next to the Studio tab at the top left is the Warehouse tab. Click it.
- Select 'Cas Part'.
- On the search bar where it says 'Filter', type 'SortL' and it will bring up the Sort Layer.
- Change the Sort Layer to 2100 and click Save at the bottom right. This should help stop it from looking weird with clothes and such.

 

Click 'Save' at the bottom. I also go to File and Save just for peace of mind.

 

NOTE: When I did this for the Masc Frame version of my Maleficium Hands, there were weights issues that didn't happen with the Fem Frame hands which basically made the glow sort of 'webbed' between the fingers. Unfortunately, I am not very knowledgeable about weights, and CASTools won't solve every Weights issue to my knowledge. 

Emission Layer

The Emission Layer is what will make the edges glow in-game. It's easier than it sounds - at least, it is for this purpose. 

 

17. In GIMP, open up the glowing hands texture.

 

Usually, next to the Layers box at the bottom there's Channels. If not, go to the top menu bar and go to Windows > Dockable Dialogs > Channels.

 

The Alpha Channel is the important one, as it is the one that controls the glow.

So how it works is: the colours on the Alpha channel can range from white to black and any grey in between. In TS4, this controls the flashing of the glow. A 100% white alpha will mean a quick flashing glow, and a 100% black alpha means the glow is constant. 

 

- Make sure ONLY the Alpha channel is selected, like above, with the black bar behind it.
- Go to Layer > Masks > Apply Layer Masks. But this time, instead of Selection, choose 'Black (full transparency)'. 

 

If that worked, the texture will disappear and the entire image will be nothing but transparency. Excellent.

 

This time, when you go to File > Export as, Export as a .dds file, not a .png file.

 

Make sure the circled options are the same as they are above, and then click Export.

 

Back in Sims 4 Studio, on the Textures tab, import the .dds file into the Emission layer and then click Save.

 

Lastly, make a 104 x 148 Catalogue Thumbnail so the CC is easy to find in CAS and import it here:  

 

18. The last step is easy. We open the CASTools program.

 

- Go to the Clone Package Editor tab
- Go to the Mesh Fixer Tools tab on the slightly lower down set of tabs
- Where it says Auto Assignment, click all 4 buttons and then Auto-Assign All just to be on the safe side. If you don't do this, the Sim will have a warped glowing zombie hand hovering beside them and it's kind of freaky, likely due to a weights issue that doing this will fix!

19. Lastly... Test in-game! (Close CAStools before testing in-game or the game won't start.)

 

This is what it looks like with an empty Diffuse layer.

 

Now you know how to make glowing edges for body parts! Isn't that cool? 

 Making Glowing-Edge CAS Body Items

The process for this is quite similar to the above, but there's also some differences. I'm going to be using my metal wolf mask as an example for this one, making a kind of magic shadow version of it. You've already learned most of the steps to this in the above tutorial, so I won't be too repetitive. Credit for the original mask is here. This is a bit more complicated than the above.

 

Again, you can use pretty much any CAS object or accessory for this purpose, so pick either a piece of CC or an in-game item you want to add a glowing edge to.

 

1. Export the CAS item mesh from Sims 4 Studio (Lod 0) that you want to add glow to.

 

- Open the mesh in Blender.
- Select the s4studio_mesh_1 in Object Mode.
- Hit Tab to go into Edit Mode.
- Press A until the mesh is selected.
- Press Shift + D then IMMEDIATELY after, don't move the mouse or anything, press ESC.
- Then straight after, press P. In the Separate menu that comes up, press 'Selection'. You'll now have 2 meshes. The new one should be called something like s4studio_mesh_1.
- Press Tab to go back into Object Mode.

  

My wolf mask does not have a proper, detailed texture and is just one colour. 
Because I want this to be a shadowy-looking mask, I am going to make the s4studio_mesh_1 black and the new mesh a toxic green colour in Blender, so I can see what it will look like in-game. I renamed the new mesh GLOW MESH.

 

2. Make the s4studio original mesh invisible for a second by clicking the eye icon on the same row as it in the Outliner box. Now go back to your Glow mesh.

 

- Go to Properties box and Materials. 
- Delete its material.
- Click + New on the materials and choose a (test) colour for the glow. I'm going to use green.

 

You probably won't do this on your original mesh since you may be working with an item that actually has a proper texture, but I will since I want to see what it looks like on a shadowy base. 
My s4studio mesh is black, and my glow mesh is green. 

 

2. With the Glow mesh selected, Press Tab to go into edit mode, select the entire mesh with A and then go to Mesh menu > Normals > Flip Normals.

 

- Now, depending on your item, you may have to do the Shrink / fatten thing again, or you can try messing around with Scaling the mesh by clicking S. If you click S, you can click Z Y or X keys straight after to scale it along a particular axis, which is what I recommend.

 

I did Shrink / Fatten just for the sake of this tutorial, but I am not fixing the seams since this is a test and there's no way I'm fixing tons of holes on a complex mesh just for this tutorial...The Scale version I did yesterday looked pretty good. Here#s the Shrink / Fattened glow mesh. Funky!

 

 

However, we need to make space on the UV for BOTH meshes.

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case. 

 

3. Go to this page on the Sims 4 Studio website and download the .zip file of UV templates. (These are the ones with the CAS categories mapped out on them). These are all the right size in this folder.

 

- Download the relevant template. (Make sure to download the DEFAULT one and NOT the HQ!)

 

Then we're going to focus on the UV / Image Editor a bit.

Separating the two UVs of the meshes

 

- On the bottom of the UV / Image editor, go to Image > Open Image and open the coloured, sectioned UV layout you just downloaded.

 

4. Select the base s4studio mesh and press Tab to go into Edit Mode. Check the 'Keep UV and Edit Mode Mesh selection in Sync' option again (which appeared in the seam-sealing step earlier)

 

- Click the picture icon at the bottom of the UV Image Editor, and then select the frame template .png. It will appear underneath your UV.

 

 

The wolf mask occupies the Hat category in terms of texture space. If you're thinking 'that's the worst UV layout I've ever seen, what's wrong with you?' that's because it is. 

The texture doesn't need to be that big because 1) the base mask is only 1 colour, but I am not the most experienced with UV maps. 

 

I could make it way smaller to save on texture size and file size since it's just 1 colour, but I'll keep it big for this tutorial since it's clear for you to see that way.

 

You essentially need a slightly 'out-of-the-way' part for the Glow Mesh's UV, so it doesn't overlap the base mesh. Since it will likely just be one colour, it shouldn't need much space. 

 

5. Tab out of Edit Mode.
- Select the glow mesh.
- Press Tab to go back into Edit Mode.

 

The Glow mesh's UV is exactly the same in terms of size and location as the s4studio mesh's UV, so it's easy to know where to put it to keep it out of the way.
You don't need much space for a glow mesh really, since it's only 1 colour.

 

6. Combine both meshes together (You don't need to do the tab-in-select-tab-out-deselect part this time)

 

- Press Tab to exit Edit Mode.
- In Object Mode, select the Glow mesh.
- Then, on the Outliner box, press Shift and Left Mouse Button click on the s4studio mesh.
- With your cursor in the 3d view, press CTRL + J.

 

Now tab back into Edit Mode and look at the combined UV to make sure neither mesh touch or overlap. 

 

SAVE CHECKPOINT: Save the .blend file! And then save another copy of the .blend file as a backup just in case.  

 

I recommend going back into Edit Mode, and then selecting the whole mesh and going to Mesh > Clean Up > Remove Doubles / Merge by Distance to lower poly count. However, double-check your mesh after to make sure it hasn't made any unwanted alterations. 

 

Once you're happy, Export the UV layout.

 

The tiny version of the mesh is the UV for the glow. 

 

On the bottom of the UV editor, click UVs and then go up to Export UV Layout. 

 

As you're saving, you'll see the part at the bottom on the left of the screen with the Size. Make sure it is definitely 1024 x 2048! Then export the image.

Creating the edited texture 

Now, open up GIMP again for texture shenanigans. 

 

7. Open the UV template layout (with the separated sections) in GIMP.

- After that, go to File > Open and open the UV layout of the wolf mask you just exported in GIMP.

 

We're going to use the sectioned template to make sure we don't colour outside of the boundary for our item.

 

- Press CTRL + A to select the whole of the exported Blender UV.
- Press CTRL + C to Copy it.
- Go back to the UV sectioned template.
- Press CTRL + V to Paste in the exported Blender UV as a new layer.

 

If you are using something that already has a proper base texture, then:
- go to Sims 4 Studio, open the .package file and export the Diffuse texture for the file.
- Open the Diffuse texture for the item and Paste it as a new layer underneath the Blender UV.
- Rename this layer to 'Texture'.

 

I don't need to do this step because I'm just drawing two different colours on top of the regular UV. 

 

Lower the opacity of the Blender UV layer.
If you are not drawing on top of an already-existing texture, then add a new transparent layer named Colour.

 

Your order of layers should be:

 

- Colour (if needed)
- Blender UV
- Texture
- Section Template

We are going to draw a coloured space on the texture which will be for your glow. For you, this will likely be drawing straight on an object's normal texture. Where the UV for your glow is, you'll need to carefully draw (with a hard-edged brush) a coloured 'blob' that COMPLETELY covers the glow mesh's UV.

 

 

This example of what I'm talking about is Valhallansim's Bloodtotem horns that are linked at the beginning of the tutorial.
As you can see, the glow mesh is squished up right at the top, and there's a big green blob there that is well out of the way of the base horns' texture to prevent any texture bleed. Essentially, this is what you want to do. 

 

For me, because my wolf mask will be completely shadow black with no shading, it's a big blob of black and a small blob of green.

 

Press the N key to use the Pencil tool.
- I recommend using the 'Hardness 100' brush, to make sure we properly cover the surfaces.
- You could also instead use the Free Select Tool (F key), Ellipse Select (E key) or Rectangle Select (R key) to select around the relevant part of the UV, and then colour in the selection.
- We're doing this with the section template underneath to make sure we don't colour outside of the boundary of our object - for me, it's the Hat category.

 

8. Draw the colour you want over the parts of the UV you want to colour.
MAKE SURE you draw the colour ENTIRELY over the UV section you want to cover! 

 

 

SAVE THIS AS .XCF TO PRESERVE ALL THE LAYERS, since you might need it later for the Emission layer step.

 

- Once you're done, Delete both the Blender UV and the Sectioned Template (make sure the background is transparent) and then save the texture as .png.

 

Back to Sims 4 Studio.

 

9. Back into Sims 4 Studio.

 

- Open the .package file.
- Under the Textures tab I HIGHLY recommend going to Specular and Normals and choosing 'Make Blank'. Do the same with Emission unless it's already blank.
- Import the .blend file you made into LOD 0 and LOD 1 if you haven't already.
- Now import your edited texture into the Diffuse.

 

Nice! Save the .package file.

 

(You may POSSIBLY need to repeat the CASTools steps from earlier, but since (I assume) the Wolf Mask doesn't move like the fingers do, I didn't have to.)

 

Now test it in-game. 

 

Awesome! You can stop here if you want, but I want to give it some PROPER glow. So - Emission layer here we come! 

Creating the Emission layer

The Emission layer can be tricky since it can be a different size depending on the CAS item you are editing.
Earlier, the glowing hands mesh based on the Ring category was 1024 x 2048. That was nice and easy. Not every part is so easy, though.

 

The easiest way to see what size you need is to find either an in-game item - or piece of CC - that is the same texture category as your object and then Export the Emission layer and see what the dimensions are.

 

This wolf mask takes up the Hat category's texture, so I go into Sims 4 Studio and look for a Hat with an Emission layer. 
The base Sims 4 has the Logitech headset which has an Emission layer for some glow.

 

- I save a .package of the headset.
- I export the Emission layer.

 

The Emission layer for this headset is 512 x 256, so that's the size my Emission layer needs to be.
That's a bit more difficult than it being an easy size like 1024 x 2048. 

 

Remember the .xcf file we saved earlier? Let's open it again. Here is my process:

 

- Select the layer that has the coloured-section template.

- Press the U key for the Fuzzy Select Tool. (Like last time, Feather Edges and Sample Merged OFF)
- If you click any of the boxes on the coloured-section template it selects the whole square / rectangle excluding the text, which is fine. (Don't drag the select tool, just click, otherwise you risk selecting too much and it NEEDS to be spot-on.

 

I then go to Image menu at the top, and then click the 'Crop to Selection' option on the menu. This crops the whole image to fit the square / rectangle you selected.

 

I quickly go into Image > Scale Image to check it's exactly 512 x 256.

 

Then:
- I delete the Blender UV and the coloured sections template
- and I get rid of ALL the base texture (the black) leaving ONLY the glow texture.

 

Now I have to repeat the Emission layer steps from earlier in the tutorial, making the Alpha channel completely black and then saving as .dds. After exporting the 512 x 256 .dds layer...

 

 Huzzah! Because of the yellowy-green colour of the Emission layer, the glow is a bit yellowy, but it looks good and it lights up!

 

You could possibly have a Emission layer that is a shade of grey if you want a gradual fade in-out glow. (The whiter, the faster the glow. The blacker, the slower the glow.) 

 

 

Making Other-Coloured Versions + Merging them all into one .package 

Because of the Emission layer, you cannot have different swatches for this kind of custom content, otherwise they will all use the same colour glow and we don't want that. 
But there's a quick way to do it, and as of 29/09/26 this tutorial has been updated to show you how to also make them all group together in CAS as well, as opposed to appear as separate .packages like in the original version of the tutorial.

 

BEFORE YOU DO ANYTHING: 

 

. Open up your finished glowing CAS item .package in Sims 4 Studio, and then go into the Warehouse tab.
. Click the CAS Part tab, and then on the right, Search for the PrototypeID. 
Copy it and keep it open on Notepad or Wordpad or something, we'll need it!

 

This was something someone else learned from Simblr surely-sims, and we need this Prototype ID to be the same across all the .packages of the different colour glows so that it all comes under the same 'spot' on the CAS catalogue.

 

 

 If you look at the glowing hands I made for this tutorial, since the .packages are all separate to allow them all to have different colour Emission layers, they come up separately in CAS and are cluttered as hell. 

 

Once I changed all the Prototype IDs to match, for some reason it didn't work with the glowing hands CC? (not sure why). But it DID work with my glowing edge dragon tails! See how they are all now neatly grouped together. Huzzah!

 

 

. First, take your finished glowing CAS item .package and Copy it and Paste it into your Documents > Sims 4 Studio > Mods folder. 

 

Then, Close Sims 4 Studio and re-open the program again.

 

When you re-open Sims 4 Studio, select 'Create CAS Standalone'  under the blue CAS button.

 

- change the 'Content' drop-down from Game to Custom. Your glowing CAS item .package should come up. Select it, and then save the new .package file with a different name. 

 

The only steps you have to repeat are:

 

- Taking the 'blob' of colour you used for the glow Emission layer. (If you saved the .xcf file  (or .psd in Photoshop) then this will be easy.) Make the blob a different, vibrant colour.

 

- Save this coloured blob as .dds

 

- Import the .dds into the Emission layer as a new .package.  

 

- Make sure you change each .package's PrototypeID to match the one you copied onto WordPad/Notepad earlier so they should all group together in CAS. 

 

This next step is useful, but not entirely necessary: In the Categories tab, on the Colours section, check the colour that matches the colour of the glow so it's easy to search via colour in CAS in-game. 

 

 

Save the .package. 

 

Possible Issues + Possible Causes / Solutions

- If you used an Emission layer and it's flashing in-game (and you didn't want it to) then it's because you didn't make the Alpha Channel completely black.
When adding the Layer Mask to the Alpha Channel, select the 'Black (Full Transparency)' option.

 

- Some issues are caused by the fact that you didn't run the CASTools mesh fixes on the .package, so weights issues are weirdly distorting your mesh (I forgot this step and my Sim had a floating giant red weird bendy hand on their left side). 
If you get this, go back and repeat the CASTools program steps on the package.

 

- If your glowing body part is layering over a lot of clothing and such, it is likely that you didn't change the Sort Layer. Go back to the Sort Layer step and change it to 2100. 

 

- If your glow in-game doesn't cover the full area that needs to glow, it's likely to do with the Emission layer being the wrong size. 
Use either an in-game item or CC item that a) belongs to the same texture category as your item and b) has an Emission layer - and Export the Emission layer to see what size it is.

- Also make sure that when you are saving your .dds file, MipMaps is set to 'Generate Mipmaps' on the Export options box.

 

- If the .blend file isn't importing into Blender properly, you might have combined the meshes the wrong way around and therefore there is no s4studio_mesh_1.
When you are using CTRL + J to Join meshes together as one, you need to select the edited glow mesh FIRST and then Shift+Left-click the s4studio_mesh_1 mesh SECOND and THEN press CTRL+ J, so you are left ONLY with the s4studio_mesh_1.  

 

- I also recommend going back into Blender and making every mesh under 'rig' (head,head+2,bottom,top,teeth,feet) is UNSELECTABLE with the cursor next to them greyed out. This used to cause issues with me importing poses, IDK if it does for CAS items but it's worth doing.

 

- If the poly count on your glowing CAS item is too high, you can try selecting the entire combined mesh in Edit Mode, and then going to Mesh > Clean Up > Remove Doubles (Merge by Distance in later versions of Blender). This might change your mesh in ways you don't want so be sure to look at it thoroughly before saving and importing into Sims 4 Studio. 

 

- If the textures or glow edge looks a bit weird, it might be to do with the Normals and Specular textures.
I suggest making both of these blank using Make Blank in Sims 4 studio.

 

- If the glow edge in the second tutorial bleeds onto other CAS items, you might have accidentally coloured OUTSIDE of the boundaries of the part your category belongs to.
Go back in GIMP and put the coloured section layout underneath the texture and then use Eraser to erase anything that bleeds out of the category's rectangle/square area.

 

- If there's bleed of texture on your glow mesh for a glowing CAS item, then you might have accidentally made the Glow Mesh UV overlap the Base Mesh UV. Or you might have accidentally coloured over the base texture by mistake.
The two UVs need to be not touching AT ALL and you need to make sure you haven't accidentally coloured over your base texture's UV as well (or accidentally coloured the wrong colour over your Glow Mesh UV's area).

- The glow looking 'spiky' on the first part (making glowing body parts) might be because you joined the wrong vertices during the 'sealing' of the split seams from Shrink/Fatten (this happened to me at least 6 times and I had to get my friend to fix it.)

- If your glow isn't coming up at all, one potential issue may be because of the 'Additional Texture Space' that the custom content is pointing to does not match where you've put the Emission layer. (For example, if someone makes a pair of antennae but clones it from a Lip Ring, the Additional Texture Space will likely be in Lip Ring and not in Hats.) More about this can be found here as I ran into this issue myself making my glowing Dragon Tails. 

 

 

If you found this tutorial helpful then PLEASE reblog the Tumblr post that this tutorial is posted on so others can find it too! I hope you have fun making everything bright and glowy!