I've been trying to remove the hood from Maxis' Death robe. The problem is that, since Death has an invisible body, the Sim will have a huge gap in the neck while wearing it. At first I tried to add a neck to the robe using the mesh of a nude top, but it will look awful, with vertices sticking all around or gaps. Also, the added neck doesn't fit the Sim's head when you make him fatter or thinner with the sliders, because it stays the same and doesn't change with the rest of the body.
How could I do this mesh, so it will look good?

Also, I can't get rid of the skeleton hands' texture editing the alpha channel. I can remove other parts of the texture, but for some reason, not that one.
(Ok, ignore this last line. It was because the hands' texture was in the overlay, not in the base texture).

so you converted it to hat/hair?
i dont understand why it interfears with the existing head/neck

No, it's a full body clothing, not hair/hat. But all outfits include a part of the neck to join them to the head. Since this part of the neck was lacking in the original outfit, I added it in Milkshape using the mesh from a top shirt. But now that part of the outfit won't morph when you move the thin/fat sliders in CAS.
Here's how the neck looks when the sim is thin (image 1) and how it looks when he's fat (image 2). It only looks more or less correct when the slider is in the middle. (Ignore the glitches of the clothing, that's just the UV map lacking).

its not that ez to combine the 2, you probably used CTU to clone?
Next step is to create morphs, you can use toolkit for that.
You best follow Cmar's tutorial meshing for dummies then.

Another thing is that you need to scale down the chest and back uvcoordinates on the map, otherwise textures from the outfit will appear on the skinpart.

I do have a testfile you can have, i basicly combined 3 meshparts(hands, body and neck) into one mesh and used Toolkit to create morphs and did this for high, med and low lods.
I always use tsrw btw so its in sims3pack.
You still need to fix textures, you can continue with CTU if you like(convert to package then)

A million thanks, that one looks great!
I didn't know about the morphs. I'm only familiar with Sims 2 and don't recall having to do anything with morphs when combining clothes for that game. I'll remember it next time.

Try tsrw(dont forget to install the milkshape plugins) and export the mesh.
You ll see that there are 4 morphs(fat/fit/thin and pregnant) besides the base mesh.
A morph is a duplicate of the base mesh but with edits n its shape.
When importing the whole bunch back tsrw will generate a morph data file(Bgeo) wich stores the morph data.
This data is used to change the shape of the base mesh when ingame(sliders)
The morphs themselves are not used in the game.

Ok, I'll do that next time. I have also read the tutorial to make Frankenstein meshes using Toolkit and S3Pe. It all seems much clearer now.

And a little off-topic, I wonder how these morphs actually work in-game. For example, I have a sim who was made in CAS quite thin and without muscle, but after some minutes in the treadmill has suddenly gained muscle. If I stop him from excercising, will he revert to the original CAS state, or will stay somewhere in-between on the slider?

i have no idea, dont feed him/her i gues and she will be thin again