12/3/2016:
To make for easier remixes, this design is also available in it's native Fusion 360 format here: http://a360.co/2g4JcHj
6/28/2016:
I switched
...Plus from tinkering with Autodesk Inventor to Autodesk Fusion 360 and decided to rebuild the adapter model in Fusion 360.
I've uploaded two new versions. Both have a thicker curved band that prevents the adapter from moving at all once installed in the rift. The 40mm version is for the same type of (almost) round lenses as the original, available from Zenni optical with frame #450021. The 43mm version is for the lenses available with Zenni optical frame #550021; note that the lenses from this frame are slightly more oblong than the smaller lenses, and the adapter is oblong to match, so if you have true round 43mm lenses from some other source, the fit will not be perfect.
Original:
This adapter is designed to take 40-41 mm diameter (almost) round lenses, such as the ones that come with Zenni optical frame #450021. The adapter spacing matches that frames spacing as close as I could get it. I have a medium-strong prescription and clearance between my prescription lenses and the rift lens is somewhere around 1.5 mm. I'm not sure if would be clearance issues with stronger prescriptions. This adapter is the result of a couple weeks of design and tweaking to get it working for my face, and it's also my first fully realized 3d design and 3d printing project, so I make no guarantee this adapter will work for anyone but me!
To use:
Before you remove the lenses from the original frame, make orientation marks with a sharpie or something on the edge so you know which way is up. My understanding of how lenses are ground for your specific prescription/IPD makes me think it's important to retain the lens orientation, and there are no other orientation marks on my lenses that I can see.
The lenses should fit loosely into the groove in the inner rim of the adapter, and become tighter once the adapter is fitted onto the facial interface.
There are tabs at the bottom of the adapter that should straddle the plastic rim at the bottom of the facial interface.
The top curved part should be oriented so its sitting flush against the indentation on the facial interface that gives clearance for the cord.
Once the adapter with lenses is fit in the facial interface, re-attach the assembly to the rift by pushing in the flat tab at the top, then gently fit the bottom tabs into place.
