Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:1468471.

Heating milk in the microwave is a convenient way to make espresso coffee, but it never gets hot enough due to localised hotspots boiling over before the bulk of the fluid is heated through. This device continually stirs the milk or coffee during heating to ensure the fluid is uniformly heated throughout. Now you can enjoy scolding hot microwave coffee without the mess.

https://youtu.be/rn385hXYRq8