Onto more interesting things...I stumbled upon this low tech, minimal tool way to size polymer rings.
Depending on your ring design, this is a method that might help you and will allow you to make any size ring you want and cost you little to nothing.
Basically, you draw a correctly sized circle onto a piece of card stock and then you stand a circle of clay directly over the circle and bake it that way.
First you'll need something to make circles the correct size. Ring sizes are only millimeters apart so measuring correctly is important. You can find ring size charts online at Jewelry Mall and a really detailed one with international sizing at Blue Nile. I also have a ring template that lets me trace whole sizes but the detailed measurements provided by the charts would also allow you to made your own circle templates with whole and half sizes with a compass.
|I got my ring template at a local PMC supplier. Its from Cool Tools.|
Cut a rectangle of clay, slight longer than the measurement of the appropriate ring size onto a sheet of clay on your pasta machines thickest setting. So for instance, a size 7 ring, if laid out flat would be 54mm long and so I cut a rectangle about 70-80mm long.
Trace the corresponding size circle onto card stock and wrap the clay around it with the inside edge of the clay just outside the line.
Gently coax the clay together at the seam. I prefer to just get the clay to stick (by holding it in place for about 30 seconds with minimal pushing) and back fill and clean up the seam after the first backing so that I won't end up distorting the circle. When the clay sticks, gently re-from to match the circle and bake right on the card stock. This would make for a very simple ring OR serve as a properly sized inner core or base.
Let me know if you try this out! I'm really happy with how these are working out for me so far.