Years ago I read about a construction puzzle, called Hazelgrove's Box. It intrigued me to such an extent that I designed a similar puzzle.

Meijer's Box consists of a box (what a surprise!) and a number of small parts. Once the parts are properly placed inside the box, a sequence of rotations needs to be applied to lock the parts in place. The final result is a cube that can be held upside down without any of the parts falling out. To unpack the box a similar sequence of rotations has to be applied before the parts can be taken out.

All you need are some small wooden beams, wood glue, a saw and sanding paper. The cross-section of the beams should be 1 cm x 1 cm, and the total length should be at least 126 cm.

Saw the beams into pieces with the following lengths: fifteen pieces of just over 5 cm long, eight pieces of just over 3 cm, seven pieces of just over 2 cm and nine pieces of just over 1 cm. Sand the sawed ends of each piece to give them a smooth surface, but make sure that you do not take away too much of the material. The lengths after sanding should be exactly 5, 3, 2 and 1 cm.

To construct the box you need all 5 cm pieces, four of the 3 cm pieces and two 1 cm pieces. Glue the 5 cm pieces, one 3 cm piece and one 1 cm piece together to form the sides of the box, leaving a 1 cm x 1 cm hole in one of the sides.

Glue three 3 cm pieces together to form the bottom and glue one 1 cm piece exactly in the center of the bottom section. Finally, glue the bottom and the sides together.

The remaining pieces of wood are used to construct the parts that have to fit in the box.

Part A is constructed from two 3 cm pieces (horizontal), one 2 cm piece (vertical) and two 1 cm pieces (one sticking out to the back, and one in the corner between the vertical and top horizontal pieces). Do you wonder why the last piece is drawn with a slightly different color? It has a bit of a story attached to it, which you can read here.

Part B is constructed from one 3 cm piece (horizontal), one 2 cm piece (vertical) and three 1 cm pieces (sticking out to the front).

Part C is constructed from one 3 cm piece (horizontal) and two 1 cm pieces (top and bottom).

Part D is constructed from two 2 cm pieces, and parts E, F and G are formed by the remaining 2 cm pieces.

Glue each of the parts together as described. Sand the parts on all sides to take away some of the material, just enough to ensure that the parts will easily slide along each other when placed in the box.

For the same reason the corners of each part should be rounded somewhat. If necessary, you can use wax to make the parts move even easier.

I am not going to spoil the fun by telling you how to solve the puzzle. The solution is not terribly difficult to find, but I bet it is complicated enough to keep you busy for some time. Just keep in mind that you are looking for a locking mechanism to hold all parts in place in the final cube. From the shapes of the box and the parts it should be immediately clear which part forms a key in the locking mechanism. But beware, one key is not enough to hold all parts in place....

If you can't work out the solution by yourself: don't get frustrated, just click here.