So if I understand clearly, what you are doing now is just sculpting the shape you want. Once that's done you remove evrything and mold one piece?
For the sculting process, can't you use some sort of clay for this instead of chemicals fibers and all that trouble? Any clay that solidify after let's say 48hrs or something? Can't believe we don't have this stuff already?
Possibly called bondo I don;t know man, inexperienced here apologies
Can you please invent any of that Super Car Clay? I want shark shaped front fenders on my roadsta