Quantity   Component name
1 × Arduino Nano ATmega328P or ATmega168 both OK (low memory use). Put header pins only on used pins
1 × MS5611 Temperature/pressure sensor
1 × Slide switch PCB mount
1 × 9V battery
1 × Snap connector suit battery
1 × Strip board (.1" pitch)
2 × Resistor 180K 1%
1 × Piezo speaker 32mm dia NOT a buzzer!
1 × Hookup wire, assorted.
1 × Enclosure/box See 3D print example supplied.