A "smart" mug warmer, that detects presence of a mug, and its tempurature.
Powered by C, on an arduino pro-mini.

Power to the mug warmer is controlled via a relay in the control box on the back of the cardboard. The relay is controlled by an arduino pro-mini. The arduio will allow the mug warmer to turn on if it detects a mug (using the ultrasonic sensor) and if it detects that the coffee in the mug is too cold (using the infrared thermometer).

I wanted to learn to use arduino and an embedded project seemed like a fun project to try.
I (someone who drinks a lot of coffee) thought this would be useful for my daily life. Obviously this isn't meant to last forever, its mostly made of cardboard. But it gave me a chance to use 3d printed parts in a project.

If you are interested in building something similar, the stand-off I made for the ultrasonic sensor can be found here on Thingiverse:
https://www.thingiverse.com/thing:4086316