An improved version of the box described in thing:931437 - Box with "Pop" on Lid. It has more flexible sides, bigger spheres have been added to the tongue and groove, and it can be "popped" open. OpenSCAD code is included. The box was printed with PLA on a Replicator using 0.3 mm layers and 2 shells. To open press opposite faces between a thumb and knuckle until the tongue and groove releases; then press the remaining pair of faces in a similar fashion; the box should "pop" open. A firm press on opposite faces will often "pop" the box apart.