This is a small collection of stereograms that I made myself. A stereogram is a 2D picture that if you look at it right, you will see a 3D picture. Look at the picture cross-eyed, with different distances, and you will see a 3D picture. Check out https://en.wikipedia.org/wiki/Autostereogram#Animated if you are confused. Click on the screen to go to the next picture.
