(Not sure if this is the correct thread to post this, since it may or may not be the fault of meshing, but the problem seems to be CTU specific from what I've gathered)

Since last Friday, I've taken it upon myself to embark on an adventure the likes of I've never done so before. I've been playing the Sims 3 since 2015 (at least in a consistent capacity), and I've done everything from normal gameplay, to making my own textures for things, to turning everyone into zombies in cities, sorta like playing a version of Plague Inc.

This is the first time I've taken on properly modding the game, cause I finally found a way to rip models from other games (particularly JRPGs). And the adventure has been going on pretty smoothly; ripping the models, the texutres, going into milkshape, meshing, the usual is what I've been doing, while reading a tutorial on how to make my own package with a completely different mesh than the one taken. However, I'm facing an issue, and that is that the game positively refuses to load the package when in CAS. The moment it loads the package thumbnail, the game freezes momentarily and then just shuts down. I wager the source of the error is the way I construct the package file in CTU (version 1.9.3569.25056), but I'm really not sure, it's just an assumption.
The way I do it is, taken from this <a href=https://modthesims.info/wiki.php?title=Tutorials:CAS_Creation_From_Start-To-Finish_-_Creating_A_New_Package>tutorial</a>:
1. Choose the CAS part I used as a base for my mesh in Milkshape
2. Go to the "Meshes" tab
3. Change the name
4. Load the LODs in order, then press Commit
5. Add new design in the "Designs" tab
6. Save the package As the name and close CTU.
7. Reopen CTU, open my package
8. Go to Designs
9. Load the textures
10. Load the thumbnail, then press Commit
11. Save the package (as in pressing "Save" instead of "Save As")
12. Close CTU.

Thus far I've made the meshes for the 1st outfit I'm porting into the game, for all 3 LODs, as well as set up the UV maps for the textures. What I haven't done yet is alter the texture files ripped from the original game so that the parts align with the mesh (since it and the sims 3 wrap a texture around a mesh in different ways, the individual parts of the texture are in the wrong places), and made different LODs for the accessories. But then again, I'm not sure if it'd be better to make a package including all the parts (so, the outfit, head and bottom, as well as shoes and accessories), or if it'd be better to split the different parts into their respective types of CAS parts.

But for now it's more of a priority to me to finally get the packages to not crash the game before moving on with this project, cause it's literally the only hurdle I'm facing right now. Every other part of this process I've done several times now.
This is a pretty massive project for me (considering the amount of characters I'm planning to do), so I'd like to get the hang of the entire process, as in become proficient before moving on with any more characters... So any help would be greatly appreciated. I'm really really looking forward to any replies!

Included in the post is the mesh of the outfit itself in Milkshape.

Thank you for reading
John

Have you tried using TSR Workshop instead? CTU is fairly old and clunky to use and I remember struggling with it as well.

Your game could be crashing for any number of reasons. I see your mesh is an outfit; how many groups is it divided in? You can have at most 60 bones per group. With a complex outfit with more than 60 bones (like a dress), I normally put the hands in a group of their own since they have about 30 bones. UV mapping shouldn't really affect much aside from the textures showing up wrong on the body.

Whether you want to keep the casparts separate or not is up to you. I would advise making it at least a body, accessory (hat) and shoes, if only for customization reasons.

Sooo... what's funny is that even by the time you posted your reply, I had managed to make 16 mods. I'm now at 23, i've been focusing on converting my Sims 4 mods since i have a lot of game characters included, and they're pretty easy to convert. The procedure is more or less what you're mentioning, I've long been using TSRW to do it. UV mapping is actually the easiest part since i just have to relegate the texture to one of the empty parts of the ts3 uv map and it'll work, as long as the clothing mesh is independent from the skin.

The mod in the screenshots I completed about a week and a half ago, I came back to it and finished it. Mesh adjustment to fit the body could be better (the bottom part came a bit too big for my liking), but it works like a charm.

The separation I do is pretty standard, any parts comprising a top/bottom are made into an outfit (since i work with such meshes, it's more flexible to make it an outfit over separate top&bottom), and the shoes etc are made into their respective categories.

I can upload the full procedure since I've been documenting it if it's needed, no issue. And thanks for your reply!