The most popular stereo camera of all time, a tank and kind of a pain in the ass; the Stereo Realist is still one of my favorite vintage cameras. Not hard to come by, and not too expensive - but they tend to be falling apart at least a little. In this one's case the focal mechanism is screwed up, so much of my efforts are either mathematical or best-guess.
It began production around 1947 and gained popularity with the celebrity set for the novelty of the 3-dimensional 35mm positive prints given by its dual lenses set just slightly apart. Effectively the same technique that VR cameras today use and Google Cardboard has made so cheap and easy for anyone with a cell-phone.
Unlike modern VR though, the clarity of the tiny little slide prints is astonishing and gorgeous. Couple that with the preciousness that comes with the product being the very film the photos are shot on and the impracticality of duplicating the slide film (especially after you cut it all apart to get it in the stereoscopic holders), and it easily makes up for being so curmudgeonly, slow, and brick-heavy.