Body panel adhesive

I bought the 3M gun, yes its expensive for a glorified caulking gun, but it works good.
Flange the panel, overlay the repair panel, drill 1/8 holes thru both panels, hold with Clecko's.
Clean any paint off metal, apply adhesive, and Clecko together.
After adhesive sets up, remove Clecko's and add more adhesive to the holes.
The adhesive sands easy its just plastic, and use filler to smooth out.

The nice thing with the 3M set up is you leave the twizzler stick on the end of the tube. When using the adhesive next time, just change the tube and you do not waste no adhesive.