Wireless electronics, such as bluetooth speakers, are extremely popular nowadays. All such devices must have a power source and typically it is a lithium-ion battery and it's not sustainable. This boombox is designed to use existing external power sources and therefore you don't need to buy batteries. Consequently, battery service-life or battery replacement is no longer a concern.

The boombox uses a USB-C port as an interface to feed power to the amplifier. The boombox can be connected to any USB port: power banks, phone chargers, laptops, extension cords, solar panels etc. Obviously, the input voltage and current draw is limited, which leads to limited sound pressure level (SPL).

Supplies

What you will need to build your own batteryless boombox:

Geometry files for 3D printing (free under Creative Commons License at Thingiverse)
3D printer big enough to fit a 235 mm diameter sphere
Slightly over 1 kg of filament depending on your settings
Two active drivers. Either Peerless 3″ (BB1) or Dayton Audio 4″ (BB2)
One 6½” Dayton Audio passive resonator
A Sure (Wondom) bluetooth board with additional cables set
USB-C panel mount plug (from eBay) and 6 mm DC plug
Wood screws (4.2 mm for the drivers and resonator, 3 mm for the BT board)
Drawer handle, IKEA Eneryda 703.475.16
Damping material (bitumen or similar automotive damping mat and fibrous wadding, for example pillow stuffing)
Optional: Wall mount bracket, Genelec 4000-410B
Minimal soldering capabilites