Lexan (polycarbonate) is extremely difficult to have formed in compound curves, such as for a lakester or streamliner , I heard that GM spent $50,000 getting the one made for the SO CAL lakester. If the wind screen shape is not compound then Lexan is a good choice but for anything else you will have a very difficult time finding anyone that can form Lexan and not have it be wavy. All of the ex permental airplane guys use a type of ballistic Plexiglas that is strong, clear and affordable.
Rex