If desired, components 38 may include magnetic components such as permanent magnets, electromagnets, and/or magnetic materials such as iron that are attracted to permanent magnets and electromagnets. These magnetic components help hold devices 10A and 10B adjacent to each other. If desired, components 38 and/or the housings of devices 10A and 10B may include interlocking male and female parts (e.g., pins and holes, interlocking grooves, or other engagement structures) that help hold devices 10A and 10B in desired positions relative to each other. Devices 10A and 10B may also be supported by removable sleeves, plastic or leather cases, covers that fold or bend, and/or other supporting structures.

Components 38 may include sensors such as sensors 32 of FIG. 2 for detecting when devices 10A and 10B are adjacent to each other. For example, components 38 may include magnetic sensors, force sensors, proximity sensors, antenna impedance sensors, light-based sensors, capacitive sensors, resistive sensors that measure resistance to determine when a metal object such as an electronic device housing is in contact with a given device, switch-based sensors, and/or other sensors that detect when the edge of one device housing abuts at least a portion of an edge of another device housing. Sensors in components 38 may also be configured to operate through the front and rear faces of the housings for devices 10A and 10B (e.g., to detect when devices 10A and 10B are overlapping in a front-to-front configuration, a back-to-back configuration, or a front-to-back configuration).