sounds to me like you are reinventing the wheel -- stereo views on cards were about the size you mention and viewers for those are pretty easy to find. The lenses for a Holmes-type stereoscope -- the thing your grandmother had in the parlor -- are still commercially available, I believe -- Get yourself a pair of those and you'll be set. is the web site for the National Stereoscopic Association -- many many helpful folks there.

I shoot stereo with 120-size cameras -- a russian Sputnik or a French Richard Verascope -- contact print the negatives and mount the views on cardboard for viewing.