My turn for help with Pulse multiplier for test rig.

[Jonathan]

Fix the mpg down on a board and mount a larger mdf wheel next to it on an improvised pivot. Use a wide rubber band as a belt . Should be relatively easy to get a 5:1 step up.

Better still, connect the rubber band to the stepper motor to get a closed loop system. I'm sure you'd get positive feedback for that idea ;)