Gridfinity Bluetooth Speaker

In addition to organizing screws, sometimes you also need to organize your music, this Bluetooth speaker is for you. Any square 40mm (1.5") speaker with 46mm diagonal mounting screws can be mounted to this 1x4x7U Gridfinity box. As for the sound card, I use the MH-M38 Bluetooth audio module, which provides stereo audio 5W + 5W amplifier, and can use a 3.7V lithium-ion battery as the power input. I'm using an 18650 as a power source along with my newly built 18650 battery holder. The centre compartment has enough room to put other Bluetooth module and Li-ion battery for the speakers too.