Kevin Sadler wrote about it:

“I have to say up front that I am totally addicted to Alexander's designs! There is something truly special about them. He has taken the type of puzzle designed by Osanori Yamamoto and added a whole new dimension of fun to them. This consists of an Acacia box which has a plus shaped opening on the top and a minus shaped opening on the opposite side and 4 rather interesting but fairly simple shapes (made from Wenge) to be placed inside such that the opening is completely covered. Straight away it becomes clear that there are some serious constraints preventing the pieces being placed inside easily. The big piece requires 4 moves to place it inside and the presence of the other pieces inside will seriously hamper this but placing it first almost completely blocks the entry for the other pieces. OK…time to think© yet again! I thunk quite a lot about this and did it 'outside of the box' yet still it didn't help much. I tried a systematic approach – there are o

Pack the 4 pieces