Armís arm is made out of legos and duplos. I also put a rock on the bottom to keep it from tipping over. Arm uses two motors; one motor is for up and down movement, and the other motor is for opening and closing the gripper. Armís brain is made up of two H-Bridge circuits, each of which controls the direction of one of the motors. I connected each H-Bridge circuit to two buttons. This makes a total number of four buttons to control Arm. Right now arm is pretty useless because it can only pick something up if the thing it wants to pick up is in the right spot, and once it picks it up, all it can do is lift it up and drop it. I got another lego motor for Christmas though, and I plan on making an Arm2, which would be able to rotate. I also plan on adding a pressure sensor onto the gripper and making it so to close the gripper you just press a button. A circuit would make the gripper close until there is a certain amount of pressure on the pressure sensor. (because the gripper had closed on an object) Then it would stop. One problem I had was connecting the lego motors to my circuit. I found out that if a wire is stuck in one of the little holes at the end of a lego wire, it gets connected to it. I still had problems though, because this connection is a bad one. I canít remember how long it took me to build, but I think it was around a week. It didnít cost me any money, because I already had all the supplies.