Hi i would like some help to convert a sims 2 cc to sims 3, its for private use ONLY and will never be posted. I have tried converting it myself with a youtube tut but i never managed to finish it. Its for my girlfriend who has nostaliga about a specific mermaid tail, but the only cc out for download is for ts2. So i would really like some help. And maybe that someone explain what exactly im doing, im just following the video and im so lost. I posted this in sims 2 but they said to post here.
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Welcome!

The main thing our CC process suffers from are updated tools but outdated documentation - leading newcomers to struggle with some very old and clunky methods, when there are far easier ways to do things in 2026.
So it's a good thing to ask for help
Could you describe how far you got / what didn't work?

There are a few different methods for making CASParts, but the set of programs I'd use for this would be SimPE, S3OC, Blender, S3PE, and MeshToolKit.
Are those familiar from the tutorial you followed at all? Milkshape has been phased out, which is a blessing if (like me) you find the controls of that program very unintuitive.

i went to go another way, so instead of just taking a ts2 to ts3, i will take a sims 3 mermaid tail and just change that one. But when i try to apply the changes i made in blender for a cc and try to apply it is says like error amout of verticies are wrong, but they are the same. I tried the same thing with the base game mermaid tail it worked perfectly, so whats wrong please help

Which program is giving you the error?

Tsrw says verticies amout is wrong. But when import the meshes from tsrw to blender 5.0.1 and 2.70 i get different amout of verticies.

Are you trying to import to TSRW as object? If so, that won't work with CAS items. You need MTK to convert to geom, add bones/ fix seams, convert to .wso, add morphs using original tail, then import to TSRW.

And how does that work exactly? i tested some thing like this


Extract CAS mesh → .s3_ via S3PE MTK → Convert to .obj → Blender

Edit mesh → Save .obj

MTK → .obj → .geom

MTK → Auto-create morph (Fat/Thin/Pregnant)

MTK → .geom → .wso

TSRW → New package → Import .wso

Save → Test in CAS

is this correct?

If I understand correctly, you decided to alter an EA mesh? What I do, is open the "donor" CAS in TSRW. In this case, a mermaid tail.

When opening a new project, give it whatever name you want. Export L1, L2 and L3 .wsos. Save the work file, and also export as package.

Open the package and extract L1 geom. Extract all 3, and L1 will be the largest, unless there's 2 groups, which I doubt the tails are.

Import geom to Blender and alter as you want. Export as both .object and geom.

Convert the object to geom in MTK. Use the geom you exported from Blender as reference to convert and then to add bones.

(I often do things this way because I think MTK does a great job of splitting seams and sharps when converting objects. Smug's tools do a very good job, but I still get stray merged vertices on some crazy custom meshes when vertices not on a seam accidentally meet.)

Use MTK to fix seams. Note: Even Thornowl's new MTK only fixes L1. I use Blender 2.80 and Smug's tools to seam fix L2 and L3 when I want those done.

After seam fix, use MTK to convert geom to TSRW .wso.

Use MTK to add morphs directly to the .wso. Use the original .wso that you exported and saved when you created the workfile.

Open your workfile and import your new morphed L1 .wso.

Rinse and repeat for L2 and L3.

I did all that but now ehen i try it out in the game its just all one color, so what can i do to fix that? Its just a test so i did some noticable changed.

The spikes are bone issues... stray vertices weights. That shouldn't happen when using the EA mesh to transfer bone weights back to an EA mesh. The coloring kind of looks like you used a filled in multipier, not just covering the area of the mesh UV? This can also happen when remaking a package, using the same CASP number, but there are other changes in the package ID's.

Do you know how too take a sims 2 cc and put it into sims 3? All the yt vids i found was on objects and not clothing

I have only converted ONE TS2 to TS3, a long time ago. It turned out sort of ok. I later found the model as MMD, and remade it from the MMD. That's why I didn't reply to your original question.

Once you've extracted the mesh and textures with SimPE, you don't technically have to follow a conversion guide at all. At that point, you have the exact same pair of resources that someone who made them from scratch does, or someone converting from any other game, or editing an existing item, so on.

Meaning that any TS3 clothing guide, whether it mentions TS2 or not, will have valuable information on what is required of a clothing item.