Sounds good, except for one thing: the hobby shop plastic will be expensive, and they'll have a limited selection. Look in the yellow pages or online for your area, and find a plastics fabrication shop. Tell them what you're doing, ask for a recommendation, and buy their cutoff scrap. I bought a 2-foot by 4-foot (61cm x 122cm) piece of 1/8-inch (3mm) black polyethlene for $8, and it was in perfect condition. To them, it was scrap; to me, it was all I needed and far more -- cheap. Fabricators in your area will probably be able to provide the materials and the thicknesses you need.
Originally Posted by Sindri907
Last summer, I went to a steel fabricator in town, and said I was looking for about a square foot of low-carbon steel plate, maybe 1/8-inch thick. The owner walked me out to the scrap pile, picked up a piece just about that size, and asked if that's what I needed.
"Yep," I said, "that's perfect. How much do I owe you?"
"It's Friday afternoon," he said. "Have a nice weekend."
It's pretty hard to beat a price of zero. I'm a firm believer in using scrap; the cost is low, and sometimes you can get good advice on fabricating and finishing techniques.
Getting back to the plastic: I suspect you'll be happiest using ABS. It machines and sands well, and it can be glued. I'd stay away from polyethylene and polypropylene, because they don't accept glues. About the only way to connect them is with plastic welding. I'm stuck with PE because that's the material used in my dash; otherwise, I'd work in ABS.
Take a look at TurboCad6's threads, especially the one on the FX35. You'll find some other good information on working with ABS in this Fabrication forum, too.