We currently are selling a proto-type eight ring on our website. This ring is two solo rings welded together. The design for this prop was first shown a few years back at the Renegadesignlab website. This shape was created by Jay Gilligan and Peter Åberg. in 2007 (?)
Since then, it is has taken off in the contact juggling community. Most people are using two 40cm juggling rings taped together. I just made a autocad drawing for a eight ring to be water jet cut, out of 3/16 sheet ABS plastic. I went for a 15 inch ring diameter. In one sheet of plastic will produce 9 rings. We will be testing this first batch to see how this size, plastic, thickness and weight works out.
I did not include the hole in the middle but maybe this is a good idea? Problem is that is ruins the illusion if your are using it for contact juggling. There are a few Japanese EightRing youtube video clips that are pretty cool looking.