Summary

Six copies of this shape form a collapsed octahedron. Assembling the six pieces is coordinate motion puzzle as each piece interlocks with four others. Getting five together is easy (see 3rd image above), but getting the last in is a challenge (see 4th image)

Instructions

So far I have only printed these on an Ultimaker. To get this to work, I printed the piece "upside down" on its point of rotational symmetry, and then added struts. Although the struts make the shape a little uneven once cut off, I haven't yet found a way to get prints in other orientations to work.

I printed at 200% and with a raft to keep the struts attached to the unheated bed of my printer. Very occasionally the piece falls over when being printed (1 time in 25 copies so far). You could solve that with extra struts if you wanted. The fill was 20%.

I included the OpenSCAD so you can remove the struts if you had access to another printing process.

This item was inspired by a paper model of a collapsed octahedron that came from Martin Watson.

Octahedron Coordinate Motion Puzzle