i remember seeing someone (jeff hanko or enrique m. maybe?) said they did a trial run with some super conductor bar stock, but the materials that showed through didn't make it worth their while. i think they said it ended up just looking like mokume gane.
Congrats on your early success Jeff! I'm sure these will be wildly popular for years and years to come. I look forward to grabbing one at some point in those years haha.