I've been scouring the internet for ideas, but have yet to come to consensus (sorry, I had to). Here are some reference pictures:
He has this kind of raised exposed muscle pattern for skin. I originally thought a painted bodysuit, but it wouldn't have the dimensionality, unless I painstakingly shaded it to appear dimensional, like this guy did:
(it looks amazing, but it would be severely time-consuming...)
Another thought was pinching and sewing or gluing the fabric, but I have no idea if that would work and have the right effect.
I also looked up liquid latex, which seems feasible, but I'm not sure if you can get this kind of sculpting out of it. Also, it seems like it would make the costume extremely hot to wear.
Yet another thought was some kind of foam rope cut in half the long way, then glued flat-side to the bodysuit in a weaving pattern. Then the surface of this would be painted, possibly with latex house paint which I heard somewhere could be used for bodysuits. It sounds kind of crazy and I don't know how good it would look, though.
Using hot glue to make a raised design was another possibility, but I'm not sure if it would have the right effect.
I would love any suggestions I can get, thanks in advance!