The sentinel is a remote operated vehicle that carries a video camera and pentium 4 computer on board. I can drive sentinel 4 miles from the house and interact with people. Sentinel has dual color cameras, complete speech synthesis and soon an active matrix flat panel to simulate it's own character. Some of the parts used are: large truck wheels, car parts, golf cart motors, audio/video transmitter, pentium 4 mainboard, dc-dc converter, custom software, custom pic micro boards, much more. Cost and time to build? Well, we all know there is never enough time and money for this hobby!! It's always ongoing. I have many other bots as well, just goto... http://www.atomiczombie.com Cheers! Brad Email: biohazard@atomiczombie.com