A transparent rubber ball

The figure inside the clear rubber ball (shown actual size) appears to be suspended above the 'flat' background. Rotating the ball creates a three dimensional effect.


 
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The ball acts as a single surface convex lens. The figure and the background are both magnified. They appear to be further behind the front surface than they really are. 

Note: The activated image has a three dimensional character because of the relative movement of the parts, even when viewed with one eye.