There are two styles of rings that you can make: a two-piece stainless steel JDG ring or a one-piece stainless steel Lifestyle ring.
JDG two-piece rings require a special ring mandrel, which you select according to the size of the ring that you are making. This is a higher end product and ring cores are made in Ontario. You can learn more about how to make JDG rings here.
Lifestyle one-piece rings can be made on a 7 mm pen mandrel using bushings small, medium or large according to the size of the ring you are making. These ring cores are made in USA. You can learn more about how to make Lifestyle rings here.