A member of my family owns a 1990 Avanti concept car, only of which 90 were ever made.
A small plastic latch on the gas cap broke, and it would not snap shut. I modeled the original broken part in SOLIDWORKS, taking measurements with a caliper, and printed a replica that he uses on the car today.
Piece fitted to gas cap:
Because this piece worked so well, I printed it in metal through Sculpteo (recommended!)
It turned out really well! And it was only $40!