Comment by George Bell: This is a unique puzzle idea, I believe. I have a copy of this puzzle and have found it difficult, but enjoyable. For some reason I have a mental block towards seeing the solution. Rick has some tips about how the solution can be "deduced logically" but this didn't help me. Eventually, I peeked at the solution(s) in the IPP29 souvenir book. Indeed it does work. Very clever! Rick does not make his puzzles by gluing blocks together, each piece is made from a solid block of wood.