I'm hacking a new lens onto my Logitech C310 webcam, but the standard lens mount has an M8x0.5 thread. This part allows me to use the more standard M12x0.5 thread.
LensMount_TightFit has a slightly smaller hole, which makes the lens a bit less wiggly.
This prints pretty well on a Replicator 2. Depending on the tolerances of your printer, you may have better or worse luck.