Heh, I definitely would not be expecting the arm scene in ESB to be anywhere Terminator in terms of blood-- i think just hinting at a bit of meat around the edges of the skin would be enough to get the message across without going far beyond what one would expect in a PG-rated movie. Also, due to the design of Luke's arm, I don't imagine there'd be blood on the actuators themselves, and since it looks like there's only a thin layer of skin there, as opposed to the Terminator which has muscle tissue over his skeleton as well. However, if Adywan feels like he can manage something meatier than what I demonstrated and still make it look believable, I wouldn't complain.