How it works: 

Your eyes are separated by about 3 inches.  If you hold your arm out in front of you with your thumb up, and close one eye and then the other, you will see your thumb shift relative to the distant background.  Your brain can process this to give you depth perception and it can recognize those shifts out to about 20 feet.  A 3D anaglyph works by taking two photos from two different positions, effectively looking at the scene with your eyeballs separated by that amount.  By assigning one image to the left eye and the other to the right eye with a color filter (the red-blue glasses) you create the 3D view.

How to make your own glasses

All we need to do is put something that lets through only the red part of the visible spectrum over the left eye and something that lets through only blue over our right eye. Options for this are purchasing red and blue cellophane at a crafts store, or printing red and blue on clear transparency film. To make it a little more sophisticated you can print a template for some glasses on construction paper stock and cut out and tape cellophane to your glasses “frame”. A web search on “make your own 3D anaglyph glasses” will give you some templates and examples. Here’s a link to NASA’s instructions for making your own glasses:

https://science.nasa.gov/resource/build-your-own-3d-glasses/

You can also order glasses online from Amazon, including more durable ones with real glasses frames and plastic lenses.

More 3D anaglyph images

A search on “3D anaglyph images” will get you plenty of examples, you want ones that work with Red-Blue or Red-Cyan glasses. A few good libraries of stuff:

NASA Planetary Photojournal has a gallery of images of a variety of planets:

https://science.nasa.gov/photojournal/galleries/pj-anaglyphs/

USGS Astrogeology branch has a few nice shots from Earth’s moon:

https://astrogeology.usgs.gov/search/map/moon-apollo-anaglyph-3d-images

This web site has a whole variety of image libraries:

https://www.delpiano.com/php/photo_3d_stereo.php

How to make your own anaglyph images

It is pretty easy to make your own. All of the above images were made with an iphone and total time for production was about 5 minutes. You just take two images of the same scene, and for the second one you move the camera sideways to the right by ~1/60th of the distance to the point you want the image centered on. In most of the above shots I positioned my son, stepped out 60 paces, then took two pictures separated by a pace.  Then you just need software that loads the first image into the Red channel and the second image into the Green and Blue channels in a manner where you can move the two images around until the focal points of both images lay on top of each other. I think Photoshop can do this. I used a piece of freeware available here (as always, buyer beware on freeware, although I have had no issues): https://stereo.jpn.org/eng/stphmkr/index.html. If you use that software, I used the Stereo → ColorAnaglyph → color(red/cyan) to make the above images.