Three is the magic number for the delightful Delta Pocket Puzzle. Give the triangular pieces a tug and the puzzle begins to slide apart in three directions at once. Something catches, however, and the metal trio remains locked together. The design of the Delta puzzle is such that once you find the solution, you'll want to take it apart and put it back together, again and again, just to appreciate the simple elegance of the engineering. Designed by Kyoo Wong of Hong Kong for Hanayama of Japan.