Hello hello! ^_^ Thanks for stopping in!
Awesome, that’s great that you’re going to be cosplaying Chell! :D
Ah, unfortunately, I bought my jumpsuit. The one I got was from a seasonal Halloween store, I just checked and it’s made out of polyester. It’s pretty comfortable and it seems to look good in pictures. (I can’t seem to find the exact one I got online, it was more of a kid/teen size, but a similar one is here. If you’re cosplaying Portal 2 Chell, the words on the back and front won’t be seen, because it’ll be tied off at your waist.)
I’ve also got the official Portal jumpsuit that I’ve bought, though I think it was limited and the only place I’ve seen it at online recently is Entertainment Earth, and they’ve only got Large and up for the sizes.
Sorry I can’t be more help than that, I haven’t made my own costume, just put the pieces together as I found them.
Can any of my followers offer any cosplay jumpsuit advice? (If anybody else sends anything in, I’ll also tag you in it so you can see. ^_^ )