Rather than plexiglass for your first model, why not use Styrene? It's a plastic type material sold at most craft stores. Your prototype will work with the styrene, I think and when you make a mold, you can then make it out of stronger more expensive material if you feel the need.
Very awsome design, and I'm looking forward to seeing how this turns out!
Then let me add to the list of new people who need to learn a thing or two. Albany area here. I'm interesting in heading to a possible NY war in the upstate, if any of you guys still post here.