I wanted to design an adapter that wouldn't hurt my feet like some of the other designs I found on Thingiverse and around the web. This accomplished that goal and ended up being more secure than other prints I had tried. 

For a more secure fitment, fasten with zip ties. The Tracker is held in place with a 1/4-20 Thread Screw. I used a D-Ring Hinged Screw found here.

You can buy them without the hinge if you want but you need that part to fasten the tracker to the adapter.

It was meant to print from the flat side facing the print bed.

If you don't want the positioner nubs just put the surrounding face to the buildplate.