What do you mean by a double screen IPhone? Do you mean you want to wire another screen onto the IPhone to display the same image or do you want to have the second screen serve another function?
That would be difficult to make the new rear housing without a 3d printer or a CNC router. And the gestures you are talking about what would they control? It would be cool to use then for activating short cuts to apps or Siri maybe.
