I first saw this neat packing puzzle over at Jerry's Small Puzzle Collection, originally designed by Martin Watson. It's also reviewed on Gabriel Ferndandes' Puzzle Collection, and is available from Puzzle Master and Creative Craft House.
I realised that it would be ideal task for the laser cutter, so I drew up a copy and cut it out from laser-grade plywood. The pieces and middle layer of the box are 4mm and the front + back are 3mm. It's actually quite simple to draw - everything is based on a uniform square grid. Here's a PDF file of the laser cutting paths. Cut the red lines first, then the blue. The kerf width of the laser is just enough to ensure a snug fit without too much wobbling about.
Several pieces are glued together to form the box, and small magnets + bits of steel are embedded in the corners so the lid is held on.