Magnetic Stirrer w/ Hotplate for <$30

Step 2 The Stirrer

To create the stirrer, epoxy the magnet set onto the shaft of the motor. Make sure it is well centered.
Next, complete a circuit with the power supply, switch, and the potentiometer. See the schematic if you have questions.
To mount the setup into the enclosure, use hot glue to secure the motor in the center of the enclosure. Drill holes to mount the switch and the potentiometer.

Place the second magnet set in the liquid to remotely stir it.