Here's a look at out 2 jointed arm. The Shoulder is chain driven by the cim on the top half of the robot and the second stage of the arm is driven by a window motor. The claw was controlled by a pneumatic piston that opens and closes. The metal on the arm was .060 i believe, and had aluminum circle tubing that spanned to each side that we riveted into it. This would be something to look at. Message me if you want some more pictures. You could use this for some ideas.
