Well, if you have lots of time to burn or simply feel creative enough, you can try making this shrink plastic ring.
Shrink plastic, for the uninitiated, was originally marketed as a toy for kids. It starts life thin and flexible. You draw on it and then bake it in the oven, and it shrinks to become about 1/3 of the starting size, but 9 times as thick. This thickness makes it strong and hard. It will not bend after baking, so if you try to pull your ring open, or stand on it, it may snap, but it is strong enough to withstand regular use as a ring.