Animated versions here - johnnyhodgson.tumblr.com 4 photos taken at the same time from slightly different angles giving a 3d effect - if you can trick your brain into seeing them.
Usually staring at the centre of the 4 images and letting your eyes go blurry does the trick - like those old 'magic eye' graphics - "Cross your eyes slowly until you see five images; focus on the middle image and you will begin to see it in the third dimension. Stereo viewing requires practice; if you cannot see it within five minutes, come back to this image at a later time and do try again.."
Sometimes you can get a much better effect by looking at these from further away from the screen - 3 foot or so.
Made with either Nishika or Nimslo 3d 35mm film cameras from the 1990's.