Printed on my Lulzbot TAZ 4 in PolyMax by PolyMakr at .2mm layers, 3 shells, 25% infill. Sliced with Simplify3D
The photos are of the first version and you can see there is a little splitting near the screw holes. The STL files and the OnShape CAD has been updated to add 3mm to the securing arms.
You'll need 2 608zz bearings, a length of m8 threaded rod, 4 m8 nuts and 2 m8 flat washers. I used 30mm self tapping flat head screws perhaps #6 gauge?