Back in 1979, I read BUILD YOUR OUR WORKING ROBOT by David L. Heiserman, a worthwhile book that gave me some of the basic ideas needed to begin my project. Originally my plan was to build an R2D2. The project soon evolved into Doctor Who's robot dog K-9. I was fortunate to come across some BBC blueprints with most of K-9's measurements and angles. The dimensions on the head are are kind of screwed up. Overall it turned out better than I expected.
The body of K-9 was built from 1/2" plywood, sheet metal with some Bondo to fill in the cracks. The ears are formed wire (I think it was a brass welding rod) with fiberglass screen glued in place. The eyes light up behind red plexiglass. A power car antenna with the orange tip of a toy dart extends as the probe. The tail is a small radio antenna wagged by two solenoids. A hinged metal panel on the side allows access to the inner components.
The body lifts off of the frame revealing a mess of wires and components. Four 6 volt 8 AH gel cell batteries provide power. There are two rear wheels and one front wheel. The front wheel has a geared motor built on to it. An old GM wiper motor with a sprocket and chain from a 10-speed bike steers the front wheel. All motors and solenoids are controlled by a Commodore VIC20 through relays. The VIC20 has been totally torn apart and reworked. New ROMs provide drive and steering logic as well as sound effects and speech synthesis. Movements can be preprogrammed through a calculator keypad or controlled by an Atari joystick. I never got around to adding RF remote control or ultrasonic collision avoidance.
K-9 has shown up at several sci-fi shows and conventions in the 1980's. Since then, parts of him have been stored in my dad's basement and my brother's garage. Currently he lives in a corner of my garage...waiting to be reactivated someday.
check out http://www.intervantage.com/chris/k-9.html