In this picture, we can see the original concepts of what C3P0 might have looked like. (Reminds me of the robot from the movie 'Metropolis'.) And, in the right picture, there is even an R2-D2 outline, amidst some other outline drawings. (If you are wondering why the image looks so blurry, it is due to the fact that my hand wasn't steady enough when the camera took the snapshot and I didn't catch the blur soon enough to do a re-take.)

To find more information about C-3P0 and R2-D2, please visit the official following web site's pages at:
http://www.starwars.com/characters/c-3p0/
http://www.starwars.com/characters/r2-d2/index.html
http://www.starwars.com/characters/c-3p0_i/