My experience with lexan is different than yours. Yes you can hit it with a hammer and it bounces back. Clamp one end in a vise and try bending it. It'll shatter. You want a "softer" plastic.
As far as forming it, its usually formed by heating and vac. forming it. It would be easy enough to make a mold to vac. form it in. You'd make it from wood.
You need a oven big enough to heat the mat'l, a wooden mold and a vac pump. I'd do my trimming after forming.
I have spent alot of time in my past making tooling for 1 part. Now in my older age I wouldn't waste my time. I'd look around for something that I could salvage off something else and make it work. Any farm-
implement grave yards around you?