6. Here you can see the progression as the inner piece of sheetmetal is bent in to place, trimmed with tin snips, the air saw, and a 41⁄2-inch grinder with a flap wheel, and then tack-welded in place. If we just cut this lip off, we’d be losing a pinch weld and also opening up our wheelwell to the elements. Welding these two pieces of sheetmetal ain’t easy. It’s really thin, and it’s easy to burn holes through it.