Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2212260.
The collet locks that came with the Prometheus System didn't work well for me. I had lost a couple of those because they weren't secure enough, they are wiggly and easily push out from the collets.
These are the improved design that is slightly thicker 1.3mm instead of 1,2mm so there will be no wiggle. The design also includes larger arcs at the opening so that once it is correctly installed, it will hold onto the collet.
Printing You need to print this in Nylon for durability and flexibility. Print it with 0.1mm layer height in order to get 1.3mm layer height.
Installation Just force it onto the collet. Use a pair of sharp nose pliers or tweezers to force it to lock onto the collet properly.