Quantity   Component name
1 × ESP32-WROOM-32E module dual-core, built-in BLE, plenty of headroom for DSP on the accelerometer data
1 × LIS3DH 3-axis accelerometer SPI interface, low power, configurable interrupt thresholds. The onboard tap-detection feature is genuinely useful here
1 × Custom PCB we designed ours in KiCad, roughly 30mm x 45mm, two layers