1.5V battery, 1M variable resistor in series with the meter movement and a 1k series protection resistor. Use a DMM to measure the low current flow and then vary the pot and write down the deflection versus current indicated on the DMM. Works well for me, I found the cheap analogue meters are pretty sensitive, being around 400uA full scale. Use the DMM to measure the coil resistance as well to help when you calculate the dropping resistor value. Simple and quick, as well as parts that are very likely on hand in your worktop.