Okay, so I realize I may as well be talking to the wall until someone else chips in, but...
I have been looking at some of the reference photos, specifically those found
here. It's interesting that parts of the suit, which appear white in some shots, are actually a cream color. You can see the stark difference in color very well in the picture of Cooper walking alone in the snow on Dr. Mann's planet. I am pretty certain (based on the fabric's apparent texture) that the elbow, knee, and shoulder pads are covered with dacron sailcloth. The texture of this white color
here or this cream color
here seem right. A yard of either is pretty inexpensive, lightweight, durable, and doesn't fray when you cut it (according to reviews). Of course, there are heavier weight dacrons if that is what you prefer.
I have also been looking far and wide for the white fabric used on the sleeves and pants. Someone earlier in the thread suggested waffle weave fabric, but I don't think that's right. Whereas waffle weave has indentations like a waffle, the fabric used on the actual suits is the opposite — it appears raised, almost embossed, or even quilted. I can't tell which, and I'm having a hell of a time locating anything similar. I found
one fabric, but it's a knit, not woven, which means it may be too stretchy. Look at color #32. I will update you all when the samples arrive.
Mike