The Weasley family in Harry Potter have a magical “clock” in their living room which displays the location of each family member. Redditor tbornottb3 converted a thrift-store clock into a custom clock for his family.

His build notes and photos are here. The clock gets its data from a web service called If This Then That, which allows you to create workflows (which they call “recipes“) for various events. In this case, the family’s phone location data alerts the clock to their whereabouts:

Most of the rules are location-based (setting me to WORK if I enter my university library, HOME if I enter my dorm), but you can set other triggers too (set me to HOLIDAY if the forecast calls for snow, set me to MORTAL PERIL if the stock of the company I’ll be working for next year drops too low).

The discussion thread on Reddit has some good improvement suggestions by other commenters, and more information about his build choices (deciding, for instance, that LEDs were easier to program than movable hands). If you’ve been thinking about dipping your toes in the pool of simple programming and wiring, this would be a fun project. Adafruit sells both the Particle Photon starter kit (which includes a breadboard) and addressable LED strip required for the clock’s guts, and they’ve also got a huge library of tutorials to help you get up and running with the code.

Old pendulum clocks are common in thrift stores, and since you only need the case it doesn’t matter if the mechanism works or not. And if clocks aren’t your thing, you could use the same general idea to create an auto-updating magic mirror instead.

(via Geyser of Awesome)