Just some simple rings with a "wave" to them. These were to test the capabilities of my Replicator 2 with small objects, though of course my kids wanted to keep and wear the results.

Print directly on the build platform -- they are unlikely to stay put on painters tape and would just become part of a raft. I remove the smaller rings by placing a regular ring around it and tugging.

At small sizes accuracy suffers and extraneous threads frequently happen, but I have successfully printed rings for my daughter down to 15mm. Printing mixed sizes (such as 20mm and 30mm) has resulted in the printer no longer extruding after the completing the smaller item.