kinked chains
I took my chainmail necklace in to work today to show to a co-worker. He liked it immediately (what geek wouldn't like chain mail?), and then there was a 2nd impression forming. "Can you do this on people?" My necklace is large enough to fit over my head, no clasps. He's sure there would be great interest in similar necklaces that will not fit over someone's head - to be worn permanently....
Of course, it would not be that hard to remove something like this. It's not a chastity belt. If you pull it hard enough, the rings will deform. If you work with a couple of pairs of pointy pliers, you can twist a few rings just a little bit to open them and un-weave them from the chain. But it has a symbolic solidity.