Bondo is fine and if you have small seams, etc J.B. Weld can be used. It sometimes makes a better sanding surface than Bondo type fillers (which can suffer air bubbles). Also...and some may find this a negative, but I certainly don't...if you use J. B. Weld, you can use J. B. Kwik-Weld and slow the set-up time by adding slightly less than 50% hardener or you can use the regular J. B. Weld which sets up much slower. This gives you time to get things just right. With Bondo and typical fillers, I find they tend to set up too doggone fast...often while you're trying to paddle them on the metal.
