A user input device , comprising: a housing that defines an internal cavity of the user input device and includes an aperture ; and a button-based control mechanism , comprising: a button that comprises a button top and a button stem , the button top extending into or through the aperture in the housing such that the button top is externally accessible with respect to the housing , the button stem being disposed within the internal cavity of the user input device ; a button depression guide that is disposed within the internal cavity of the user input device that engages with the button stem to cause the button to move from a default position and along a substantially arc-shaped path when pressure is applied to the button top , the substantially arc shaped path being around an axis of rotation that is external to the user input device ; a button biasing mechanism disposed within the internal cavity that causes the button to return the default position when the pressure is removed from the button top ; and at least one sensor that detects actuation of the button responsive to movement of the button away from the default position. a housing that defines an internal cavity of the user input device and includes an aperture ; and a button-based control mechanism , comprising: a button that comprises a button top and a button stem , the button top extending into or through the aperture in the housing such that the button top is externally accessible with respect to the housing , the button stem being disposed within the internal cavity of the user input device ; a button depression guide that is disposed within the internal cavity of the user input device that engages with the button stem to cause the button to move from a default position and along a substantially arc-shaped path when pressure is applied to the button top , the substantially arc shaped path being around an axis of rotation that is external to the user input device ; a button biasing mechanism disposed within the internal cavity that causes the button to return the default position when the pressure is removed from the button top ; and at least one sensor that detects actuation of the button responsive to movement of the button away from the default position. a button that comprises a button top and a button stem , the button top extending into or through the aperture in the housing such that the button top is externally accessible with respect to the housing , the button stem being disposed within the internal cavity of the user input device ; a button depression guide that is disposed within the internal cavity of the user input device that engages with the button stem to cause the button to move from a default position and along a substantially arc-shaped path when pressure is applied to the button top , the substantially arc shaped path being around an axis of rotation that is external to the user input device ; a button biasing mechanism disposed within the internal cavity that causes the button to return the default position when the pressure is removed from the button top ; and at least one sensor that detects actuation of the button responsive to movement of the button away from the default position. <EOS>