When I lived in San Francisco in the late 70's, I came home from work one day and saw a (beautifully restored) Bugeye with a trunklid. I looked at it (lid closed) and it looked like a natural, or factory done job. It also had the wooden dash from a Jaguar sedan (minus the "center" section). So it well could've been the work of a craftsman/enthusiast.
I went inside to get my camera and the couple of minutes it took was enough time for the mystery driver to get away. I never saw it again.