THE RING AND CHAIN: Two lengths of 16 gauge wire twisted together. A 1 ¾" long piece was cut from that and the ends filed flat. It was then formed into a ring and soldered. After cleaning up it was attached to a 16 gauge paper clip chain (rings made on an 8mm mandrel) with 16 gauge 4.5mm ID jump rings.
Being "snap on" is kind of a misnomer because it does not mean the bail will open and close with a snap. A purchased snap on bail is made of a very hard metal with two overlapping ends on the back side. The inside end is pushed down while the pendant is slid onto the outside end. When the inside end is released, it will spring back to touch the outside end, securing the pendant to the bail. The snap on bail that the coin pendant came with made it easy to attach the coin to the ring.