Looked around Home Depot and found this today. It's some kind of metal trim for drywall.
Obviously, this bench is for clean stuff, not hammering/beating on. Not that I do much of that anymore but I have a small all steel bench on big 6" steel casters for that. A Craigslist find future project that needs "attention".
I had a leftover 4x8 sheet of OSB from my recent shed build and I bought an 1/8" sheet of underlayment to finish to make it look better. I used a Behr poly stain on it but I have to admit that stuff is crappy. Instructions tell you to leave a wet edge but that's basically impossible. Even though I went two coats with sanding between you can still clearly see the brush strokes. Oh well, it IS a garage bench. I put 3 coats of clear semi gloss polyurethane on top. The metal will finish the edge hiding that it's two sheets, not one. I'll use self-drilling screws every foot or 18 inches to attach it to the OSB.