Same model as the 4cm interlocking hex, scaled down to 35mm face-to-face and a bit over 4cm between opposing vertices.

The lock is the same, you can slide this piece on the larger one. The 2 teeth version is there because, otherwise, you won't be able to make a stack and put a lid on something 1 level lower. Given how well they fit and stay, leaving it with only one tooth would suffice.

Same license, you can use this, remix this, upload modified versions, print this, sell the prints. You CANNOT sell these 3D models in any form, nor claim authorship of the designs.