An input device, such as a stylus, can include a main body comprising a main body connector for connecting to a charger to charge a power source of the stylus. A separate functional end module is removable from the main body to expose the main body connector. The functional end module includes a functional component and a module connector that communicates with the main body via the main body connector. Various different functional end modules can be interchangeable to provide a variety of distinct features to the stylus.