History of Slide Projectors
View-Master StereoMatic 500
View-Master StereoMatic 500, made in the 1950s, was a stereo projector, allowing viewers to see images in 3-D, which displayed images onto a special silver screen which required viewers to wear special polarized glasses.
The View-Master system was introduced in 1939, four years after the advent of Kodachrome color slide film made the use of small high-quality photographic color images practical.
"Be sure that each one of your audience is equipped with polarizing glasses designed for viewing stereo projection, and that the screen you use is suitable to stereo projection-usually with a metallic surface. When your audience is seated and have put on their glasses, turn off the lights and start the show."
Here is link to the PDF of the manual for the projector: