I've been trying to make a custom facial hair, by using a clone of a basegame moustache.

I got to the point of modifying the mesh and having it ready, but now I don't know what to do with the textures, since they are all... odd.

I've been searching through this site and a bit on google and I didn't find anything.

I know this is possible to make, because I've seen plenty of custom 3D beards and moustaches.

Do you know of any tutorials?

I don't think I've seen tutorials out there, and I myself have very little experience with beards, but you don't necessarily need to change the textures--beards textures are separate from clothes and such, so at least the textures won't overlap or bleed over into the makeup or hair or anything crazy.

Do you perhaps mean that the UV mapping makes the textures look weird, or that it was converted from somewhere else and the UV maps are all over the place? I had that happen a few times; it's annoying. But just make sure you have a greyscaled Multiplier, and a black and white Specular; and a RGB Mask (with red-green-blue, though I've sometimes seen beards use just the Red channel).

It's best to open up a CC 3d-beard in TSRW to see what the innards of the file looks like; what textures are used, what bones/joints, etc. Even looking at EA's from World Adventures, Late Night, etc.

Thanks for your reply!

I started working with the clone of a basegame moustache, which is actually a 3D one. And, even though I've never worked with any kind of hair before, I started off with the hypothesis that those texture maps were not to be modified along with the mesh.

When it comes to the UV map, I didn't really have much to worry about, since I wasn't doing any major changes. This was just a test: I was chopping the sides of the moustache, to turn it into a "Hitler". It ended up looking like this.

I didn't touch any of the texture files that you can see on that image.

However, when exploring the textures attached to the mesh (material), I discovered that there is a specular map , which looked exactly like a 2D image of the moustache. So I opened it up in Photoshop and chopped the sides , to match the mesh. Then I saved it to DDS, like you normally do.

I know this ain't pretty, but it was just a beginner's test, to learn how things work.

As you can see in the image, it looked ok in TSRW. But, when I tested it in game.... the mesh was changed, but the texture covered the entire body!

In all honesty, all my CC making experience is limited to clothing, tattoos, makeup and shoes. I've never worked with hair of any kind, so maybe someone with hair experience can tell me what's wrong with this ????

I reckon 3D hair on the scalp shouldn't be that different than 3D hair on the face. Maybe?

Yeah, this probably needs to be in the CAS Parts of the creation forum, so people with more experience with hair can weigh in on what could've caused that issue.
I ran into the same problem recently with trying to clone CAS items that ended up with textures bleeding all over the sims' body. So I have no idea.