0.25mm nozzle, clear PETG, Prusa, 6mm standard headphone jack, upcycled broken bluetooth headphones, three times larger battery, snap fit with no hardware, FreeCAD, 2nd print iteration, listening to it now, no tricks - it holds together firmly and is usable and actually sounds better than the original by a long shot from better headphone drivers I guess or proper soldering, oh and power button built into the flex of the design, OC only posted on Lemmy
From the post, it sounds like it’s just whatever they ripped out of an old pair of Bluetooth headphones… So probably a proprietary purpose-built PCB rather than something more generalized like an esp32 or something.