Started modeling the 3D printed focus motor holder in Fusion 360. The plan is to have one side of the motor on a pivot, and the other side with a tension spring pulling up on it and keeping it in contact with the focus wheel. Ideally the force would be enough to give good traction between the motor and wheel, but allow for manual movement, or simply allow for a latch to keep the motor out of contact with the focus wheel. I've designed this holder with a clamp to hold it in place on the microscope, but if that doesn't work I may need to drill/tap into the microscope to hard-mount it.
I plan to use M3 hardware (2x M3x30mm socket cap bolts, 2x M3x15mm screws, 3x M3x20 screws, M3 washers, 2x M3x40 threaded hex spacer) to assemble the motor and holder/clamp. I'll purchase the missing components like the threaded spacer from McMaster or eBay, though I have plenty of M3 screws to hold me over for now.