I did this on TinkerCAD for fun. It's not screen accurate, but it's as close as I can get without driving myself crazy. I haven't printed it yet, but I will add a picture when I do. I modeled it after the one on Doctor Strange's costume at http://marvel.wikia.com/wiki/Sling_Ring. I might edit it later on to make it more screen-accurate or easier to print.
I would recommend resizing it to fit your fingers before you print.
You will probably need to use supports when printing it.
Update - 1/18/17
I tried printing it today, but I scaled it down too small. I think the best way to print it is to lay it on its side, so that the side facing you when you wear it is on the bed. Still use supports, and use a raft if your printer doesn't like doing supports without one. I'm working on fixing the rings in Tinkercad so that they're more circular. I will add the updated version when I'm done.
Update - 1/20/17
I edited the design in thingiverse, so it should be scaled correctly now. I should be able to print it soon.