An Arduino mini pro provides the brains. A FT-232 USB to serial board is used to program the Arduino. A standard Bluetooth module has to have HID firmware installed. [Dastardly] makes a homemad ...

Unfortunately, though, no USB charging cable is provided ... battery, Aldi's Bauhn Mini Retro Bluetooth Speaker is definitely worth checking out.

GCZ’s 50-Watt Bluetooth Mini Soundbar is the perfect little gift ... You can also connect it via USB, Optical, AUX, and RCA. And, as a bonus, it comes with a handy remote for easy volume ...