Each buzzer consists of an Arduino Pro Mini 3.3 V, a nRF24L01, and of course a big pushbutton on the top.

Figure an Arduino most matches the "Other" category. To be specific, it isn't an Arduino brand, it is a DigiSpark, but the trouble isn't with the device itself. The problem is with a buzzer. I got ...

Throw in an Arduino, buzzer, battery, and a boost converter for the switch, and that’s just about all there is to it. How to deactivate the Annoying Machine?