Could you really be afraid of a Rise of the Machine-esque future if your robot tormentors were made of Legos? Probably not. Nevertheless, giving you a glimpse of that possible future is this Lego model of a fully mobile prosthetic arm and hand.
The model, created by Max Shephard, is fully capable of digital flexion/extension and full wrist abduction/adduction thanks to Lego pneumatics. The arm was built completely out of legos and was designed as an above-elbow prosthesis capable of 12 degrees of motion freedom. Excluding comparisons with those of you who have a freakish hitchhiker's thumb, the range of the motion for the prosthesis is on par with a human arm and hand.
For those of you so excited that you're rushing to find your serrated saw at this moment, don't get ahead of yourself: the arm isn't going to be as reliable as your current arm. While the arm is capable of picking up and manipulating objects such as cups or a roll of tape, it doesn't handle so well with objects heavier than a couple of pounds.
Rest easy, though: this model looks to be more Johnny 5 than T-800 anyways, so hopefully the robot will be our friend and foil bank robberies as opposed to, y'know, enslaving us.