Hi SideFX forums,

I'm having trouble with vellum cloth seams. There doesn't seem to be any documentation about it, and I'm not so advanced with it yet.

Attached is the example of the type of seams I'm looking for to make. How would you go over creating a thicker shape like this?

One solution I thought about is making a new piece of cloth, shaped like that, and attaching it to the original t-shirt shape. However softwares like Marvellous designer have easier solutions for that. They simply allow you to define a taped seam.

looking forward to your reply!

Don't you just love all those single-anonymous posts by users with very telling usernames …

In the picture that you attached I can see only ONE actual (connecting) seam (between the arms and main body part) whereas the other “seams” actually are hems. You may want (or not) to constrain those areas to your animated geometry, but they're really not about setting the shirt up for simulation.
As for the single seam, please do a search on sideFX' tutorials section or on Vimeo. There REALLY are very well presented tutorials on how to use Vellum's “seams” for connecting parts of clothing.
THEN come up with a sample HIP to post here that shows how far you have gotten by trying for yourself. I am certain you will get help once you have demonstrated that you TRIED.

Marc