[PGSigns]

When I first learned to do panel repair I was helping a guy build model A's. Everything was gas welded. What I was taught was gas welding and doing it stitch and hammer. Seams were all but welded a 1/2" or so at a time and hamered when hot. Move down a foot and do it again. Once done the weld was cleaned up out came the torch and a wet rag to work the seam back flat. Same thing can be done with a mig gun and .023 wire and stich welding. Then heat and shrink. It takes practice. Google shrinking disc and watch some videos.
Jimmy