These are the printed parts used to make the Tiamat tool-changer as seen at MRRF2019. I hadn't planned on releasing these as it was really designed for a one-off motion system, but there seemed that there was enough interest that I'll leave the STLs for folks to modify if they wish.
This tool changer uses a full-size hobby servo and 8mm rod to rotate between tools (see video). 5mm (or 3/16") ball bearings in the carousel backed by springs (I used springs out of ball point pens) serve as detents into the lower sled piece to lock the position on tool changes. This carousel is designed for E3D V6 hotends. A variety of M3 and M4 nuts and bolts along with 608ZZ bearings are required for assembly.
I'll happily answer any questions if you want to make something based off of this, but since this isn't designed to be a step-by-step project I won't be posting significant details here.
Servo to shaft coupler: https://www.servocity.com/clamping-shaft-couplers-6778
Thanks to Joshua Vasquez for use of some his photos from MRRF.