When we made our box last year we went to Home Depot, and they have a small selection of different plastics n shit. Lexan is expensive as hell, but there's cheaper versions that you could probably do for 10-20 bucks. Our main problem was cutting it, as hte Home Depot guy said to use a tool to score it over and over again, then just break it along the crease. I recommend a jigsaw or circular saw, something with a thin blade that won't shatter the plastic.