I wanted a way to play music/jingles over the speakers after my local team scores a point. So i needed a combination of a MP3 Player and a bluetoothmodule. I wanted it to be useable by anyone so it had to be as simple as it would get. One LED is to be used to rise the powerusage so that a normal powerbank won't shut off. The buttons are 16mm and the LEDs 6mm. I powered this with USB C. The hole at the back is for AUX so that you can use it without bluetooth.