Florin wanted a MakerBot watch but they were never in stock. So he made his own! He calls it the DWex, which stands for the ‘Duino watch for experimenters.
This watch is built around a 3V-powered ATmega328P running at 8MHz. Time is shown using 2 circles of 12 LEDs, in a manner similar to an analog watch (with hands). Minutes are indicated on the exterior circle of green LEDs; hours are indicated on the interior circle of red LEDs.
To make the watch practical (that is, wearable), the battery life should be at least in the order of months. This can only be achieved by keeping the processor in sleep mode most of the time. At the push of a button the microcontroller becomes active and lights up the appropriate LEDs for 3-5 seconds; then it goes back to sleep.