An improved thermoplastic material for orthoses and prostheses. This material comprises at least one resin layer of polymeric resin, optionally reinforced with multiple layers or internal fibers, designed to be compatible with vacuum thermoforming, with thickness between 3/64 inches and ¾ inches. The material additionally comprises at least one and optionally two extremely thin cap layers with thickness between 2/1000 and 12/1000 inches, at least one of which is intended for improved compatibility with human skin, and the other of which can be configured for various cosmetic or UV protection purposes. Methods of producing this material, and various orthotic and prosthetic devices using this material, are also taught.