1. A sheath for a computing device comprising: an outer shell configured to be removeably attached to a computing device, wherein the outer shell includes a first side and a second side; a plurality of input elements, wherein one or more input elements are arranged on the first side of the outer shell, and wherein one or more input elements are arranged on the second side of the outer shell; and a plurality of mechanical elements physically connected to a corresponding input element of the plurality of input elements; wherein the plurality of mechanical elements are configured to press on a contact location of a touch screen of the computing device in response to chorded input received on the input elements, and wherein the computing device includes software that enables the computing device to recognize chorded input.