Build your own Binary Watch
Hobbyists who have progressed from the world of solderless breadboards and making their own PCB should move on to making their own surface-mount projects, as is the normal progression of learning to make your own hardware. One great example of this is the binary watch by Instructables user taifur, who took their Arduino knowledge and miniaturized it somewhat.
The watch is based around the typical Microchip ATmega328-series microcontroller and DS3231 real-time clock IC, with the display using simple LEDs and powered by a watch battery. Fitting, considering this is a watch. You can see it in action via the following video:
Overall an outstanding effort, and we like the PCB art as well. For more information, check out the watch's Instructable page.