My turn for help with Pulse multiplier for test rig.

[JAZZCNC]

Here's another idea.
I used to work on plant where Selsyn Motors were used for synchronisation purposes and remote indication. It occurred to me that stepper motors were very similar so a quick search found this;
Fun with Stepper Motors - Synchronous Operation without Power - YouTube
No external electrical power required just a crank handle on a spare stepper motor.

Ye played with this before and while it will turn another motor on the bench there's no torque obvioulsy due to low current/volts.