Stewart Coffin wrote in “Geometric Puzzle Design” that assembling a cluster of separate hexagonal sticks and dowels can be a puzzle but a more difficult and therefore more interesting puzzle will be made when some of the hexagonal sticks and dowels are joined to make elbow-shaped pieces. The more elbows the harder the puzzle. Stewart theorised that the maximum number of elbows that can be joined before assembly becomes impossible is half the number of each type of piece, so that’s what Brian has done.

18 hexagonal sticks of varying lengths 18 dowels of varying lengths 9 hexagonal sticks and dowels joined to make elbows Numbered as #22-B in Stewart Coffins numbering system his notes indicate at first that he thought he had only made one puzzle in 1985. Later research would indicate that just two puzzles were ever made back in 1989 and no mention is made of how many elbows, or therefore the level of difficulty, of these.

Assemble the 27 pieces into a lattice structure