Quantity   Component name
2 × Arduino UNO Code is for Arduino UNO. An Arduino Mega would work, but you will need to modify code.
2 × nRF24L01 Long range or short range version is fine
2 × Electret microphone
2 × NPN transistor Any type of simple NPN transistor would work, but I used 2N2222 and 2N3904
2 × Pushbutton standard momentary pushbutton
2 × 3.5 mm jack breakout board or speaker
2 × Breadboard Electronic Components / Misc. Electronic Components
6 × 10k resistor
2 × 100k resistor
6 × 100nF capacitor