I'm trying to fill up a bunch of the unused holes in my inner fenders/ engine bay to clean up the engine bay since the harness is going to be tucked.
Most of the holes are too big for just MIG welding shut. I was thinking of trying to find a sheet metal punch tool that would make intact tiny slugs to weld in.

Does anyone have tips on how to fill the holes easily? Or what type of punch might give me useful slugs?