^
I believe the guy who made the Guyver suit had a webpage with tutorials, but I think it went offline or something. A pity, really...
I've thought about attempting a Gills suit, but I need to get a job first, and I still need to figure out how I'm gonna go about doing it...
As for painting the belt, I can't give you a straight answer. One part of me says "DON'T DO IT! YOU'LL RUIN IT!" and the other part says "just use the right kind of paint and it'll be fine!".