This is a mashup of the "Evolution of the Men's Ring" thing with the "Lego Compatible Disc Button" thing, and a sort of cousin to the "Ring-a-thing" LEGO attachment.
Due to the wonders of OpenSCAD, I modified the LEGO Disc to be filled in, then aligned and combined it to the face of the ring. Voila!
Print out and enjoy! You might have to fiddle with some print settings to get the studs to fit snugly with other LEGO pieces.
I also aligned this ring to be printed studs-down, which caused a little bit of overhang issues. Overall, PLA seems to handle that sort of thing a little better than ABS, but your printage may vary.