Summary

I made this initially to spin part: http://www.thingiverse.com/thing:543083 around on a pivot. I decided to spend a little more time with this design & make it parametric. The included STL file is sized for the 64 tetrahedron shape listed above.

You can either edit the openscad file or open this in the thingiverse customizer to make the size you want.

Limitations
In the current version it will not size correctly if you go below 24mm for the Inside Width Clearance Distance or below 54mm for the Gimbal distance. I will take a look at fixing that soon.