I ordered the motors shown in the images a month ago and still waiting for them to exit customs, so have pushed on with design that can be updated when they finally arrive. They were less than a dollar for 10 including postage, you get what you pay for. I may order some others for design flexibility.
The design will use conformal joints / living hinges and use 3D printed components connected using monofilament line. This ensures that there is no backlash, which is critical for this level of resolution.
Figure - 1.8mm thick PCB provides foundation for the motor and resistor, fitted together with M1.2 screws, the micro linear resistor provides feedback to the controler. The motor driver IC will be on the board so that only lower current drive signals are in the wiring, and reduces the number of wires required.
Figure - The end effector is designed to hold an optical fiber to allow me to position when building a pig-tailed laser diode assembly.
It's hard to appreciate just how small this will be; being able to fit in a rough 40mm x 40mm x 40mm volume.