I was asked to identify all of my gunsmithing tools to make them distinguishable from another smithie. I could spend hours engraving them, but as you know many are hardened and don't engrave well. Add to that all the oil they are always in... and nothing sticks. So other than engraving, has anyone come up with a clever way to mark their tools that works as well for hardened reamers as chrome plated hand tools, and won't just peel off with oil soak?