This was for a school project in which we had to design a shield for the Arduino Uno.
The goal was to program a small 'roulette table' with 13 LEDs. Pushing the button would play an animation to simulate a rolling ball until it came to a halt at a random LED.
This PCB was not difficult to design, the focus of the project was on management and documentation. The documentation is in german.
Warning: each LED needs around ? mA current to be driven. As the ATmega328P-AU is only rated for up to 200mA of current drive capabality you should not activate too many LEDs at the same time.