18x12mm are dimensions of small driving robots that have AVR Attiny45 microcontroller on-board. These were developed by Naghi Sotoudeh. Small robots have two wheels – actually two vibrating motors from cell phones. They can be driven directly with MCU pins. Robots can be controlled with TV remote control.
Small 3.6V NiMH battery servers as power supply that fits nicely under bot. And this is pretty much of hardware – no resistors or caps are used. Motors are driven with PWM signal so speed and turn can be programmed easily. Programming is done with bascomavr compiler. If you want to see it in action you’ll have to download 6MB video.