The grinder with a poly carbide disc from HF will not get into tight places like corners etc. but it will make quick work stripping larger surfaces. The disc costs under $5 and I used up maybe 1/4 of a disc on this fender. It took me maybe an hour and a half. So the cost was less than even a few sheets of good quality sandpaper - not counting the electricity and cost of the grinder. See for yourself. Sure, there's more work to be done to strip it completely but the larger areas come clean very efficiently with the poly carbide disc. No chemicals, water or brushes. just wear a mask.

1965 C10 front fender

After about 1.5 hours to do front and back.

The poly carbide disc from HF

Inside the fender BEFORE

Inside fender AFTER