I've made and used them plenty. Use leather about the same thickness as a cap. I drill the holes on a drill press about 1/8" in from the edge the cut a slit to the edge with a razor blade. Can be made in any shape or size you want. IMHO, much easier to use than the fancy brass or silver cappers. And we have several of those, they look neat but are difficult to use. BTW, the leather ones will last many years. And, they are cheap. Scrap leather and five minutes work.