coroplast(polyethelene corrogated) for bellypans. lexan or acrilic for grill blocks and headlight covers different plastics for different jobs, i have a cheap local dealer down here in fl.
I suggest usin plastic interior pieces from the jy....I made my grill block from the piece of plastic that covers the inside of the rear hatch on my 1.0 Geo...took a max of 10 minutes.