Security researcher [Fran Brown] sent us this tip about his Tastic RFID Thief, which can stealthily ... 12 AA batteries and a custom PCB using an Arduino Nano to interpret the reader’s output.

[Pierre] recently bought his first car and decided to make his own RFID electric starter for it! An Arduino Nano controls two relays which in turn can turn the car on, start it, and turn it off.