Could you use conductive filament? Your questions answered about the fully 3D printed speaker!
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Proto-pasta CDP11705 - PLA conduttiva composita, 1,75 mm, 500 g, colore: Nero : Amazon.it: Commercio, Industria e Scienza
Conductive PLA Filament 3D Printer Material is 1.75mm10 Negative Guartic Making the Small Bulb Bright Black GOOD 1KG 0.5KG 0.1KG
Amazon.com: YOUSU Conductive PLA Filament 1.75 mm for 3D Printer & 3D Pen 1 kg (2.2 lbs) Black : Industrial & Scientific
Electrically Conductive Composite PLA 1,75 mm / 500 g
Conductive PLA Filament for 3D Printing Prototypes
Protopasta Electrically Conductive Composite PLA - 3DJake Italia