Build Your Own Magnetic Stirrer That’s Both Affordable and Effective

Magnetic stirrers are typically used in laboratory environments where cross-contamination is a concern. They work by spinning a small magnetic stirring rod inside a vessel of liquid using an external moving magnet or array of electromagnets. Because the stirring rod (which can be sterilized) is the only thing actually touching the liquid, and that liquid can be kept in a sealed container, the stirring process can be kept free of contaminants.

Coogle realized that those same attributes would be ideal for mixing his fiancée’s airbrush paints, and so he set out to build her a magnetic stirrer of her own. The actual mechanics of the device are very simple: a small pod is sealed with magnets inside and acts as the stirring rod, and magnets mounted on a PC fan in the base of the stirrer create a rotating magnetic field to spin the rod.

If you want to make your own, Coogle has made the 3D-printable parts available on Thingiverse. Aside from those, all you’ll need is a standard 80mm 12V PC fan, a 12V motor speed controller with an LCD readout, and four magnets. Everything mounts together using just glue, so the build process should be pretty easy. Operation is as simple as dropping the stirring rod into a container of liquid, and adjusting the speed of the fan with the motor controller.