It’s winter, and that means terrible weather and very few days where flying RC planes ... 3.5mm jack on the transmitter used for a ‘buddy box’, but [sjtrny] had an extra receiver sitting ...

If you have lots of RC creations about ... easily scalable to a large number of receivers. The transmitter can be made of anything to hand; stick an NRF24 module and Teensy inside, some gimbals ...