I discovered this puzzle when experimenting with notched sticks from the 35 piece minicube puzzle. After completing the puzzle I was surprised to see it was an Altekruse type design. The short sticks were added to fill in the spaces. A small quantity were sold in 1991 and 1992.
When making them again in 2008 I thought of adding a block to fill in the empty cavity inside to make the puzzle more interesting. Adding this block makes the assembly more challenging and has the side benefit of allowing the addition of two ball springs which adds just the right amount of friction so the puzzle smoothly slides apart. This spring loaded block also helps hold the puzzle together during assembly. So this is a nice enhancement with 3 benefits. 3D assembly instructions are included. -Jerry McFarland