In 3D Stereo: Alley Cat Relaxing

Crossed-eyes 3D (stereoscopic) viewing: View the two photos cross-eyed until a third image appears in the middle, which will be in stereo 3D. The brain nicely synthesizes a composite image with realistic depth and sharpness. Then put your two hands in front of your face to cover the photos on the left and right so only the middle one remains in your sight.

Done