Overhead crane simulation in Unity 3D

I would like to have an overhead crane platform simulated and developed in Unity. The crane should move on beams in factory and be controllable with gamepad (i.e. Xbox joystick). Person will grab different types of granulated material with crane jaw bucket and dump it into corresponding bunkers. The source code with proper structure and comments should be given for possible further modifications. I have the working process knowledge and motion equations of it.