K'nex Ball Machine Lift: Giant Ball Catapult

This is my new lift, the Giant K'nex Ball Catapult, it shot to a distance of 4 meters (because my room is too small), it only contains a motor, it's totally automatic, the arm is tracted by a nylon cable, but the shot is very hard to regulate, because the catapult shot creates a role-back, and the elastics extend.

I could give you the instructions for build it, but this lift is (In my opinion) the must dangerous K'nex ball lift ever !