I like music. In Arduino IDE example, I like the most is toneMelody. It is simple yet interesting. However it is quite boring to play monotone. So I decided to play multiple tones and create harmonic melody, like you're playing piano just convert it into individual tone to be played by each Arduino board.
I'm using Maker UNO (Arduino Uno compatible board), because it has built-in piezo buzzer connected to pin 8. It cost only $6 and I use 4 of them to play Un Poco Loco (Disney Coco).