For the Eleventh Gathering For Gardner I designed another exchange gift. It consists of 8 planar pieces, two different shapes that can be assembled into a cube-like shape in only one way.

The puzzle is not easy. Please try to solve it manually before resorting to the solution.

To assemble this puzzle some dexterity is required. The way depicted here attempts to minimize the required dexterity.

Take two of the large pieces and position them like this on a flat surface (the distance between the two pieces is two units) | |

Now take two of the small pieces and hold them like this. | |

Slide the small pieces into the room provided by the large pieces. The image shows the pieces one half unit shifted to the front resp. back, which is 1.5 units from their final positions. This need not be exact, but it prevents the next two pieces from sliding down completely before they should. | |

Take the last two large pieces and orient them like this (again, the distance between the pieces is two units) | |

Slide them in until stopped by the small pieces | |

Take the last two small pieces and orient them like this | |

Slide the last two small pieces in until they extend by one unit | |

Slide the first two small pieces in by one half unit | |

The top 4 pieces can now shift (drop) down two units (if every piece is aligned perfectly; which can be difficult to achieve). | |

Slide all four small pieces in by one unit |

The puzzle was designed with BurrTools, experimentation with unit cubes and a lot of effort.

Peter Knoppers