We use 3M Panel Bond. It is stronger than a weld and no warping. It does have to be on bare metal. Rough up the patch and about an inch around the hole with 36 grit, use enough Panel Bond so it squeezes out around the edges as this will prevent any water from getting in the seam and causing rust, stick together and let set over night. If where visible smear a swipe of bondo over the patch and sand smooth.

1949 AD firewall with bonded patches done 16 years ago:

[img]https://i.postimg.cc/T5xnpnCk/dan-s-49-011.jpg[/img]

1930 Model A with bonded steel top done 5 years ago:

[img]https://i.postimg.cc/p9qDpmgx/IMG-4335.jpg[/img]





Evan