I've been trying out engraving sword blades using conductive probing instead of my old mechanical probe, and I must say, it works great! I'm using AutoLeveller, written by James Hawthorne (http://www.autoleveller.co.uk). I updated it a bit to allow for an optional "tape thickness", and it's pretty sweet. Many less steps in the process than there used to be for me.
Anyhow, here's the scoop - I clamp down my sword blade (which is conductive, but that doesn't matter). I then apply a strip of masking tape to the blade, squeegee it down, and then apply a layer of aluminum HVAC tape. This tape is conductive, and it's about .1mm thick. So, combining the thickness of the masking tape + the aluminum tape, I get my thickness that I feed into my modded AutoLeveller. The thickness gets subtracted from every z move, and everything works great.
Next up for me is building a clamp to hold the scabbards, and then I'll use the same tape/tape/probe/cut routine on them.