The wider rings are actually copper pipe! Most of the rings in the picture actually fit my (apparently) small fingers, about a size 4 or 5, I found that 1/2" copper pipe works really well for that. A ring mandrel is a must, and a worthwhile investment. If you really want to go all out you could purchase use copper sheet to make the rings as well, but you will need to really brush up on your soldering skills for that! Also, here's a tip that I got from the guy in the plumbing department. Those black coloured rings they use for PEX plastic pipe are actually copper, and the black colour (which I suspect is LOS patina) can be removed with sanding.Those rings are nice & heavy if that's a look you're after. Hope that helps!