On the irregular clamping front, here's one that is in current manufacture - but probably to pricey to ever buy!
The ball bearing approach is intriguing and I think it would more evenly distribute clamp pressure. Harder to make though. I'll keep working on the simpler design.
Th Matrix pin vise (which seems to have ball bearings) have solved that shortcoming. They have a proprietary system that locks all the pins in any configuration between changes.The other downside of the ball bearings is that they would allow secure clamping of irregular objects but not secure clamping in a reproducible position