Update: I successfully printed the file named lanternring final which replaces the old one as of 3/26/15. Good one size fits all dimensions would be about one inch on x or y axis (whichever is the side parallel to the circle's diameter).
In brightest day, in blackest night, No evil shall escape my sight. Let those who worship evil's might, Beware my power, Green Lantern's light!
Be declared the world's greatest nerd by printing your own nifty Green Lantern Power Ring. Welcome to the corp!