I see so many conversions where a patch panel is applied over the old overhead lights... *see attachment*
I've got a buddy that's got a high end hot rod shop and I watched him use a pneumatic panel flanger like this to install patch panels
Also, I searched and they've got several models of vice grips with the dies welded to the jaws
not knocking anyone's build, but it just seems like if you've got an air compressor and a welder.... it makes for a clean patch.
Harbor Freight has a flanger for $40 with mixed reviews
Air Punch Flange Tool
just an idea
personally, I have to use what I got!