Spider coupling with Sugru insert mold

This is a derivative of MiseryBot's excellent spider coupling http://www.thingiverse.com/thing:7678

I basically modified few values to have it fit the 8mm diameter of my trapezoidal spindles - the original thing was adjusted to fit the common M8 threaded rods whose diameter is slightly smaller than 8mm. Additionally I corrected the M3 nut trap sizes since they were little too small to match ISO 4032 nuts.

Finally I used the insert-positive to quickly make a simple, but great working mold for use with awesome SUGRU!

This is the best performing coupler I used so far. Note that the spindles need to be supported via extra bearings for radial guidance as well as some kind of fixing collar on top of one bearing for axial support.