Pico is an impressive hobbyist robot. It measures in at 2 cm3 (12.5mm per side) and features a laser-cut chassis, two Didel motors (MK04S-24 driving worm gears), an A3901 stepper motor driver, and an ATtiny44 microcontroller. With a run-time of 15 minutes off a 10mAh Li-Poly battery (approx 3.7V), that equates to a power consumption of about 140 mW. I suppose the large power consumption is to be expected, given that the Didel motors employed can use as much as 100mA at 3V!
An image of Pico sitting on a dime is shown below (left), as well as the laser-cut chassis (right).
Here is a video of Pico in action.