The 3D-Zipper is an original mechanical design that interlock two unstable chains into a rigid load bearing L-shaped structure.  A regular zipper connects two elements on the same plane (in 2D), this gizmo connects two elements perpendicular to each other. The concept has been developed as part of a larger project called ZBeam. ZBeam aims to create self-reconfiguring modular elements for space habitats using 3D-Zipper as a core element. To learn more about ZBeam, visit it's Hackaday.io project page: https://hackaday.io/project/25... Here is a video showing the usage of the 3D-Zipper concept in that project: Assembly and printing Beside the printed parts you will need four M3x12 screws to attach the rollers. The chain links require a well calibrated printer with decent tolerances. I have successfully used both my Prusa i3 MK2 and Printrbot Simple Metal. For the links I used 60% infill and 0.1mm layer height. The other parts will do with at 30% infill and 0.2 mm layer height.