3D-Puzzle-Plane (Waco UPF-7 Biplane)

I had the idea of creating a 3d-puzzle with interlocking parts that are secured with rings made from rubber as I've seen on a display stand at the local supermarket. Using this biplane I published a while ago, I started to look for a good solution for each piece. The perfect solution would have been that each part locks another part, which was clearly not possible. After several iterations and some changes against the original design, I had a working prototype.

I made two versions of the puzzle using my desktop cnc-machine by Stepcraft. One was cut from 6.5 mm beech plywood using a spiral-toothed 1.2 mm flute, the bigger one from 9 mm birch plywood. The rubber-rings I got at eBay. The small rings are 5x2mm respectively 6x2mm and the larger one 10x2.4mm respectively 15x2.4mm.