I modeled and printed these enclosures for a few 4 ohm speaker drivers + passive radiators I had laying around, to bring some use to these parts.

It's my first OpenSCAD project, so the scripts are a bit rough, but workable. Enclosures are all cubical, with cube side and speaker diameter as parameters, as well as wire hole diameter.

The right speaker case has insets for a volume knob and the left channel output, plus holes for the USB cable, the cable going to the subwoofer and an aux input jack that switches from the built-in USB DAC to an external input. The left channel and subwoofer are connected via one-ended RCA cables.

For the amplification circuit, I'm using a passive crossover network and two PAM8403 amplifiers. One amp only has the subwoofer connected to one channel. An additional capacitor is added to the power supply to provide enough power for peaks. I've run these at max volume from a single USB port without any problems, average current draw did not exceed 300 mA, but might probably peak at over 500 mA.

The subwoofer goes down audibly to 50 Hz, but peaks in loudness at around 80 Hz.