1. Hold both hands vertically up, at a comfortable distance in front of your face, palms pointing away. Then make a frame by linking your thumbs together.
2. Position your frame so that each hand obstructs the view of the cylinder on that side of the image. Your right hand should obscure the right cylinder from view by your right eye, and similarly on the left.
3. Now look at your hands. Then, transfer your attention to the object visible in the gap between them, i.e. within the frame. Focus on that object until it coelesces into a single, revolving, 3 dimensional cylinder - before your very eyes!