Cyrus Tabrizi, 12/26/12

      The last part of the upper body is the counterweight. Its weight is mostly derived from the six AA batteries inside the battery box, but it is also the long distance from the center of the arm that contributes to the weight's effectiveness. The battery box is attached to both the upper arm and the base by liftarms and the geometry of this connection keeps the weight in a position that counteracts the movement of the rest of the arm. Also acting as counterweights, albeit barely, are the two receivers that sit in a position between the arm and the battery box.

157 158