I then fit the mounting ring to the skin. I spot welded it around the perimeter and then set it up there and bolted it down. I still have to tweak it some but it turned out ok for a first time attempt at something like this. It will need a little skim coat of mud to fix a couple of wavy spots but should not take to much. I will use a rubber seal of some kind after I paint the car. Good enough for now. Time to move onto something else. Hope I can help someone out a little bit with my technique.