At first, smartwatches were like little tiny tablets or phones that you wore on your wrist. More recently though we have noticed more “hybrid” smartwatches, that look like a regular watch, but that use their hands to communicate data. For example you might hear a text message come in and then see the hand swing to 1, indicating it is your significant other. Want to roll your own? The OpenChronograph project should be your first stop.
The watches are drop in replacements for several Fossil and Skagen watch boards (keep in mind Fossil and Skagen are really the same company). There’s an Arduino-compatible Atmega328p, an ultra low power real time clock, a magnetometer, pressure sensor, temperature sensor, and support for a total of three hands. You can even create PCB artwork that will act as the watch face using Python.