how to repair holes in sheet metal without welding
I’m no expert but here’s my two cents. 1st it depends on the size of the hole. If it’s a small hole, just grind to bare metal, use a spot sandblaster to get all the rust out of it if it’s pitted ($20 from harbor freight). If you need a backer you can use fiberglass mat or a piece of screen. Epoxy prime to protect metal then fill with body filler and sand. Prime and paint. If it’s larger and you need to make a patch and can get behind it, you can glue the patch panel in with automotive adhesive I use Lord Fusor. It’s about $60 a tube and you’ll have to buy a special caulk gun (about $50). grind clean the patch panel and the area around the hole where the patch will be applied. Apply adhesive , clamp and let set for 24hrs. When it’s fully cured it will be stronger than a weld. If you try to tear the patch off, the metal around it will tear before the adhesive gives way. Fill, sand and paint. I also like to coat the back side of the patch with a rust encapsulator (like Por 15) or an undercoating to prevent re rusting.