I never thought of repairing pewter with JB Weld but I carry it
in my Zen motorcycle repair bag. I had one crash which punched a
hole in my gas tank. The JB Weld patch cured enough in 20 minutes
for me to be on my way. That was 10 years ago and it is still
holding. I also hit a rock once and cracked the magnesium
crankcase. Same fix, same result.