What are you guys using to do this? I have an old school unshielded die grinder with a 1/8" wheel. It works but more and flatter surface might be better. My brother was using an electric angle grinder with a cup style wheel (but then he just recently stopped crimping and lapping panel seams). I'm sure there's a preference for each person, but I'm just looking for ideas to get them smoother without gouging.