Hi, Dave,
My favorite is Lexan (polycarbonate) - - it is tough, rather than brittle, the way styrene and acrylic plastic are. Take a piece of Lexan an inch wide and 1/8" thick and try to break it in half - - you'll be surprised. It can be drilled, sawed and machined with much less of a tendency to melt than Plexiglas (acrylic plastic). If I see ANY polycarbonate sheet plastic at the flea market or in the scrap bin at TAP Plastics, I buy it up - - extremely useful. For a front panel, you'll probably want to get a product that is heavily tinted or black - - unless you are proud of what's behind the panel and want to jazz it up with colored LED's, as in some of the transparent computer cases on the market.
Good luck
Chuck