I built a swedging tool for use in restoring vintage musical instruments. It works well, but I collets do not stand up to constant use. I was thinking about case hardening. I found a product called “Cherry Red” that I think might work. Typically I am working with brass or silver. I often need to hand make missing keys and key rods. Worn key rods are reamed true and swedged, but I don’t want marks. Here are a few examples. The tools sold do not hold up and invariably do not sell the collet sizes I need. This tool uses ball thrust bearings to prevent binding and of course brass accents for looks.