My TM20VL has an R8 spindle and I'm using Tormach's TTS tool system. I've set up the Mach3 tool table with all of the tool height offsets. The issue I was having is how to label each tool holder with the tool number. My initial solution was to use metallic stickers with the tool number printed on it. The issue is that with all the solvents, oil and coolant around, the stickers only lasted a month or so.  This article describes how I solved the problem.