just sharing what i've found about neoprene:
from my samples, neoprene is stretchy. but, by itself, it doesn't conform well near curves in cutout areas like other materials. a rigid backing layer or even sewn to fabric might help remedy this if you were to go this route in areas like a cutout in the forearms.
the inner rubbery part looks like outer layer of the outfits, but not quite it -since the movie uses a moulded foam too. the backing of the neoprene i've found is a stretch type material like lycra or spandex.
at foam mart, (aside from the colours) there's exposed neoprene, neoprene with a backing on one side, and neoprene with backings on both sides. i saw cracks in the rubber that appeared in a sample of 1/4"(?) neoprene where it met on the price tags, where staples where applied and removed.
i take that with a grain of salt, not knowing how those cracks were caused since i know this material can be sewn into wetsuits.
neoprene can produce crease imperfections in folded areas of the rubber layer, as i was able to look at an unrolled sample there.
applying a heatgun to a test sample just produces a burnt rubber smell, can distort the finish of the rubber side, and doesn't keep a curve like foam does. since the rubber portion is non-porous, a glue that doesn't necessarily rely on porousity and allows for some kind of flex might be beneficial.
i think(and am guessing) the movie used neoprene for certain, hidden underlayer parts that needed something sewn in and for flex & support. as parts of a base layer i see benefits. for the cosmetic areas, other materials were probably used, depending on the suit.
with that said, the actual costumes are way out of our budget & resource ranges. if you're able to accomplish a cool costume with whatever way works for you, that's the important part.
