This example of a Bluetooth-controlled car created with an Arduino UNO, a 25-gram board, can be dropped to seven grams with a Nano and even lower to five with a Nano Every in its place.

The build began as a simple two-motor, skid-steer RC car build with a fan for suction. Controlled by a smartphone app, a cheap Arduino board with an HC-05 Bluetooth module ran the show.