Ironman Faceplate Ring
by Vivenda, published
It's the Iron Man faceplate on a ring.
Various sizes and materials also available at https://www.shapeways.com/shops/vivenda?section=Rings
There's two ways to print this(6th image in) . Best method I've found personally is upside down (for FDM) or with the faceplate facing up (which has seen some good results on SLA printers.