I started with the green lantern model from itchyd. I loaded it into Zbrush and started sculpting different designs. My goal was to be able to build a dual extrusion model that prints with a high quality ring surface. I printed my ring with makerbot green and glow in the dark filaments. The ring hole size is 2.25cm.
"In brightest day and blackest night
No evil shall escape my sight
Let those who worship evil's might
beware my power: Green Lantern's light!"
I've included the stl and thingy files.