Magnum Steel This two-ounce tube is named Magnum Steel, which sounds like a TV series but is actually an excellent gray (steel-colored) epoxy putty that sets "like steel" in 5 minutes and fully cures in an hour. Works on metal, plastic or wood and can be drilled, sanded, painted, machined or tapped. Made here in America.
I can personally recommend this stuff. About 4 years ago we plugged a leak around a bolt in the hull of our old wooden trawler with some of this stuff and it's still holding!