In September there was an exhibition of film props and costumes at the IMAX cinema on the South Bank, and these were among the articles on display, wedged between a cylon, a daggit, and (I think) a spacesuit from Alien. There was enough detail in the scene that I felt challenged to draw it, and it had to be a linear drawing rather than tonal. The big challenge with a picture like this is getting everything to line up - it's the easiest thing in the world to get carried away with filling in the detail only to find out afterwards that you've messed up the overall shape of the object.
Technically, these are droids rather than robots - there is a difference, of course. The Star Wars universe doesn't have anything as common as "robots" in it, for the same reason that it doesn't have any "laser swords".