[Andy A.]

Acyrilic is perfectly legal to use (follow the flow chart!). However, as others have stated, it's not exactly an ideal material. Polycarbonate (lexan) is just as easy to work with and less likely to shatter or spiderweb on you.

Acyrlic does have one fantastic property- using a torch you can flame the edges. This finishes them off removing any tooling marks, rounding the edges and restoring it's clarity. It makes parts look much more professional. Since that is a pretty minor consideration in FIRST, I'd focus on using polycarb. if you are set on using a plastic as a base.

In place of either material, I would suggest either plywood or, if you want to get fancy, my new favorite material, garolite. Garolite is a cloth and resin based composite, sort of like fiberglass. It is very rigid, easy to work with and transparent to radio. It's used in some PCB's. McMaster has it in various grades, sizes and thicknesses. It's more expensive then plywood and comparable to polycarbonate. It is in between plywood and polycarbonate for toughness, but beats them both in rigidity. This means you can get away with a very thin, and thus lightweight, sheet. 3/32 or 1/8 would be fine, I think, depending on the overall size.

-Andy A.