BOM

• Perfboard square grid of 0.1 inches, pads on both sides (plate-through holes), 2" * 3.5", $3
• STM32WB55 Dongle, part of P-NUCLEO-WB55, DigiKey 497-18384-ND
• OLED display
  • 128x32 pixels if it should fit into 2" * 3.5"
  • 128x64 pixels
• 35 pcs push buttons, fit in 0.4" grid
• Wires
• USB Connector e.g.
  • USB MICRO-B BREAKOUT BOARD Adafruit #1833, DigiKey 1528-1383-ND, from $1 up
  • Adafruit Micro-Lipo Charger for LiPo/LiIon Batt w/MicroUSB Jack, $7
• I2C Connector