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. The mk3 has screwholes so that it doesn't has to be glued or press-fitted. One LED has been removed because i changed the type of LEDs used and the power usage is high enough that the powerbanks don't shut off. The AUX hole and the power hole are changed. Also the mp3 player and the bluetooth module can be powered individually