This is my fully autonomous obstacle avoiding robot built from Legos, 2 DC motors, an Arduino Uno, a breadboard, jumper cables, and an hc sr04 ultrasonic sensor.
The DC motors are powered from 8 AA batteries and the Arduino is powered from a 9v battery.
I designed/built/soldered/programmed the robot myself and would be happy to answer any questions anybody has. The code that the Arduino is running is available here: [http://pastebin.com/taZ7KJz2], and a close up of the wiring is available here: [http://i.imgur.com/1wFjA0I.jpg]
Also, sorry about the oranginess, the lighting in the room was quite bad.