In this beautifully rendered color drawing is a concept of what R2-D2 and C-3P0 might have looked like waling through the middle of the harsh conditions present on Tatooine. (Also note that this is one of the better images the digital camera managed to capture.)

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/
http://www.starwars.com/locations/tatooine-iv/