Quantity   Component name
1 × 315MHz RF kit Cheap Transmitter and Receiver
2 × ATtiny85 For the transmitter and receiver. Internal oscillator (upgraded after photo)
1 × 12VDC/240VAC relay Because ATmega does not like 240VAC :)
1 × 12VDC wallwart Relay receiver requires 12VDC, ATmega 5VDC
1 × 7805 or something similar Relay requires 12VDC, ATmega 5VDC
3 × AAA batteries +-4.5VDC turned out to be enough for the ATtiny and the RF transmitter
1 × Diode For the relay
1 × tinyUSBasp Or Arduino, AVR mkII or any way to get the sketch onto your uC