Several embodiments include a mobile device. The mobile device can include a circuit board configured to interconnect one or more electronic components and a chassis shell adapted to form an outer perimeter of the mobile device and to enclose the circuit board. The chassis shell can have an integral unibody that includes a contact feature integral to the chassis shell. A sensor system can be in contact with the chassis shell on an opposite side of the contact feature. The contact feature enables the sensor system to detect touch events when a user interacts with the contact feature.