Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2414004.
These nipple shields are designed to stretch the nipple slightly. The ring itself is 6mm tall and 12mm in diameter. I am including two versions - the smoothed version and the squared version. The smooth version is the one that you want if you're printing as is. I found that modifying something in Sketchup once you've rounded the edges is a PAIN, so I am including the squared version for those who may want to modify it to suit your needs.
There is no hole through the hub because these were designed to have the bar ride on top of the ring. Normally, I would have put an indent in the ring to help center the bar, but the idiot who did my girlfriend's piercings didn't do it straight, so that doesn't work here.
I have not yet been able to talk my girlfriend in to letting me post the photos of these being modeled..... ;)