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Construct an interlocking puzzle with 30 identical pieces.

Photos by George W. Hart

For the maximum puzzle challenge, stop reading and try to assemble it based only on the image. If that fails, follow these step-by-step assembly instructions:

a. First observe how 3 back-of-the-head notches can meet and "mind meld" like the corner of a cube, with all 3 heads facing either clockwise or counterclockwise. You can assemble the puzzle in either of 2 mirror-image solutions, but all mind melds must be the same. After finishing, you can disassemble it and try the other handedness. (For the other set of instructions, just look at these pictures in a mirror.)

b. Use 5 twist ties to hold together 1 pentagon cycle.

c. Make another pentagon interlocked with the first.

d. Position the 2 pentagons so that 2 heads of one do a mind meld with 2 heads of the other. At the opposite end of the pentagons, you can get another 2 and 2 heads to mind meld. A rubber band around the mouths can keep the heads together.

e. Continue adding parts, 1 at a time, making twist-tied neck pentagons and rubber-banded mind melds. The final few parts have to be carefully steered into position, but no force is needed.

f. The very last part goes in as 2 halves, 1 from each side, and locks together.