Convert the body to polygonal models of different sections then use Pepakura to make a folding pattern.
To achieve symmetry, figure out how to make a mirror pentagraph with a 1:1 ratio. Then you hand shape all of one side. Build up the other side with material thicker than needed everywhere. Trace the finished side with a stylus while a router mirrors the Y plane (in-out from vehicle axis) on the other side while moving the same as the stylus in Z and X planes. A 2 axis tilt on the stylus, copied by the router, would help reproduce finer details.
With a stylus and router bit of the same shape and the positioning correct so it's not carving too much or too little, it would make fast work of finishing a body plug for making molds.
In short, like a giant Copy Carver that works in more than two axes. If it fails, hack it up with a pair of axes.
