Rectangular Puzzle by PlanToysRectangular Puzzle by PlanToys. The PlanToys Rectangular Puzzle challenges your balance as you solve the puzzle. Through play, children will develop fine motor kills and hand eye coordination. You can play the Rectangular Puzzle in a number of ways. You can stack the pieces in various ways to create pattern and shapes. The ultimate test is to be able to stack the pieces together in the correct pattern to build that sturcture that does not fall apart.