When filling thick sheet metal like that i let the copper plug stay a little proud on the show side and dressed it down the back side i filled with polyester filler bondo and as it deserves repeating i can not over emphasize the importance of cleaning the sheet metal thoroughly before soldering.
Filling holes in sheet metal.
The kind of plug to use depends on how the thin metal is being used.
Perhaps a simple rivet or sheet metal screw can be secured in the hole.
By filling in holes you stop rust in its tracks and ensure the metal lasts longer.
Body filler is a simple way to repair freshly cleaned holes.
Fills small holes cracks and perforations.
Works on metal wood and concrete.
Forms a long lasting metal tough bond.
Easy to use filler can be drilled filed sanded and painted.
Whether you re dealing with a small piece of sheet metal or something valuable like a car you can fix it.
If you know how to weld take advantage of your tools for a longer lasting repair.
If the hole needs to contain a liquid a rubber washer can go on the sheet metal screw to render it water tight.