PKParis K'ontrol µUSB controller

grabcad

This 6mm thick, 30mm diameter device plugs into a tablet or smartphone's micro USB port. It replaces one virtual joystick and two virtual buttons with a physical joystick and two physical buttons. To bind buttons, simply touch the desired virtual button while pressing the tiny orange binding key, which will blink to indicate successful binding. For the joystick, push it in the desired direction if replacing a D-pad or press the binding key first for emulation, then trace a "Q" with your finger on the virtual stick's center without exceeding the max range for accurate calibration.