Magnetic Stirrer

Design criteria:It had to be usable in the field or the lab.Therefore, it had to be compact and easy to store and transport,……and that includes the magnetic stirrer bar…..And it would need to run on batteries,As it also had to double as a lab stirrer, it also required power for long term use.It had to stir volumes from 10 to 1000 ml.It had to be feasible to fabricate.It had to be resistant to spills and chemicals.Vitamins2x M3x5mm screws for the PWM controller2-3x M2x8mm screws for the charge co