The function in the readout: its traces, pads and partsFeather RP2350, TLV320DAC3100, EYESPI on top; LiPo, e-ink, NeoKey 1x4 on the backA 61.06 × 76.16 mm board milled from single-sided copper: 0.4 mm traces, a GND fill, and four 0805 0R jumpers where a trace has to hop another. Adafruit boards plug into SMT sockets; the EYESPI flex wraps the top edge to the e-ink. The LiPo and STEMMA QT cables are not drawn.