I received several designs from Pit Khiam when he heard that I had recently gotten my Laser cutter. And of course I was thrilled. Threshold was the first one I set out to make. His puzzles are always very clever and well designed. This one is especially tricky. 30 moves to get the first piece out through the slot at the bottom! This one should keep you busy for quite a while. I added a slight overlap on the edge of the top tray to help hold the pieces in, just in case you start thrashing it about in frustration!