Systems and methods that reduce a number of holes that penetrate into a housing of mobile computing device by employing a modular housing with a housing plate(s) attachable thereto. Such housing plates can form a segment of a stylus trough and also facilitate attachment of hand strap and socket cover arrangement to the housing of the mobile computing unit. By reducing number of openings into the housing, a risk of liquid or particulate contaminants entering into the device and degrading performance of the mobile computing unit can be reduced and reliability increased.