A simple puzzle based on an optical illusion. The pieces appear to completely fill the frame, but when you rearrange them, they leave a blank square. Try it yourself and see.

There is a single color version for both the X1C and he A1 mini. There are also 2 color versions for both printers that require two plates.

The solution to this apparent paradox is that your eyes see what you expect to see, not what's really there. For an explanation of this puzzle see: