Muscle powered electronic dice
If you are tired of shaking dices in your hands in order to randomize them before throw, you can shake some electronics instead. The realisation of this device is very interesting. It doesn't have any batteries, it is realised using ATtiny13 microcontroller and it is capable of generating enough power to power the micro and LEDs.
Power generation is accomplished by using Faraday power generator. It is basically a wire wound on a tube with neodymium magnets moving in that tube. In order to generate a dice's number (roll a dice), you must shake the device to generate some power. On the authors website you can find a double-dice version of the device.
[ Source: Gadre ]