Ladder

This is a very dificult wooden puzzle - one of a family of puzzles, all having a similar starting point, However this perfectly symmetrical, multifaceted stucture is formed by the assembly of 51 bars. Each bar was carefully cut so that the pieces can interlock to make a solid core.
Once assembled, no single piece can simply be pulled out of place in order to take the puzzle apart.  As in many construction puzzles, the key lies in turning one piece.