havent tried the spray and hair dryer trick, but i tried dry ice and it flat out doesnt work. waste of $12 and my time

 

I guess this is more for a caved in body panel. I tried it on a dent that I have on the fender. It is actually a crease from the bottom edge of the battery. The nut that installed my snow plow, dropped the battery on the fender.

In either case the canned air didn't do it.