Before I get rolling, I want to clear up one thing: Bondo is a brand name, though it's commonly used as a general description referring to any and/or all body fillers-kinda like Kleenex is to tissues.

Back in the day, there weren't any quick plastic fillers to hide your mistakes under when doing body work. The old-school method of finishing a panel's contours or welded joints was to use lead. Lead ...