I am not talking about scientific applications. I am talking about tens of millions of sterescopic photographs and viewing devices[1] made in the late 1800's,

I am not talking about scientific applications. I am talking about tens of millions of sterescopic photographs and viewing devices[1] made in the late 1800's, with stereoscopes being about as prevalent and accessible as radio sets and TV's before the transistor era. You can still buy a 3D card more than a century old for under $5 in vintage stores around the US. And yes, you can slide your cell phone into a stereoscope and enjoy your 3D/VR apps 1880-style. (Today's VR headsets for cellphones are just 1800-s stereoscopes with a rubber band). [1]https://en.wikipedia.org/wiki/Stereoscope https://en.wikipedia.org/wiki/Stereoscope