I been learning the ropes on a stereo Holga, but in the process of acquiring one I looked at a lot of possibilities, including the Loreo 3D converter and an old Pentax beam splitter. None of them really seemed all that worthwhile considering how bulky and optically meh they were. But then there’s the other extreme – cutting apart and welding two cameras together, which seems a bit overkill when you consider what older technology is out there (via Horses Think).
As for viewing the images, it’s a bit costly to shoot slides for slide viewers, so I’m leaning toward the old fasioned stereoscope with printout cards. There is of course, cross-viewing by naked eye on a computer screen, but somehow it always leaves me feeling even more ridiculous to Ooo and Ahhh cross-eyed in front of a computer than to Ooo and Ahhh while a gigantic wooden structure sits in front of my face.