Today I've made a ring with shrink plastic:
You need shrink plastic, a ring, super glue and an oven.
Draw your design onto the matt side of the plastic. The figure shrinks to a third of their original size and get thicker when it's in the oven later, som draw it three times as big as you want your result. These are the measures of my ring:
Cut out the design. Place it on baking paper on a baking sheet. Heat in the oven at 175 degrees celsius. When the plastic is lying still, it's ready. Take it out from the oven and place it immediately under something flat and heavy.
Glue it on the ring and let it dry. Ready!