MacBug, you shall NOT derail this thread. But you do remind me of some ancient carved handbag handles my great aunt had, made from some kind of bone or ivory. There was a lot of piercing-work, probably done with a file by a 6 year old. The same sort of work could be done on an arc to make a cantle, especially if the material were polymer. How that would be attached to the sporran is up to you. AND, if one chose to work out some kind of low relief/ scrimshaw design, the laser engraving technique might work for a cantle, too.