I found this on Thingiverse, and decided to give it a try:
http://www.thingiverse.com/thing:1602460
They are made for lenses from glasses you can buy on zenni optical: http://www.zennioptical.com/450021-metal-alloy-full-rim-frame-with-spring-hinge.html
The glasses from Zenni, including my prescription lenses were about $17.
The results are fantastic! Much better than wearing my glasses. The lenses from Zenni are very good. I wasn't expecting much for $17, but I was pleasantly surprised.
If you have access to a 3D printer, and wear glasses, I recommend trying it out.