I recently made a choker-style necklace from some WS2811 addressable LED strand I had on hand which is 1cm wide. I designed and iterated on this clasp mechanism a couple of times before settling on this design. It uses a clipping mechanism inspired by the CLASP Simpler Watchband design

After initially modelling and using a simple clasp-like connector, I found the choker would sometimes pop open if I tensed my neck, so I've added a little tooth which hooks in to one of the sewable holes in the male end. By sewing in the receiving female part with the tooth facing outwards, a tight fit will press the tooth in to it's other half and make the clasp attach more firmly, while still being easy to intentionally remove.

I printed this thing using a Makerbot Replicator 2 with Makerbot "Natural" clear PLA filament, using the Makerware software on the 'High' profile with shells set to 8 so it's shells all the way through - every part is totally solid, which looks super nice with the clear filament.