Currently, virtual (i.e. touchscreen) controls are dynamic, but lack the tactile feedback and advantages of physical controls. Similarly, devices may also have dedicated physical controls, but they lack the flexibility to adapt for different contexts and applications. On mobile devices in particular, space constraints further limit our input and output capabilities. We propose utilizing reconfigurable tactile micro-elements around the edge of a mobile device to generate dynamic physical controls and feedback. These tactile micro-elements can be used for physical touch input and output, and can reposition according to the application both around the edge of and hidden within the device. We present two implementations of such a system which use magnetic locomotion as means of actuation. One approach utilizes PCB-manufactured electromagnetic coils, and the other uses switchable permanent magnets. We perform a technical evaluation of these prototypes and compare their advantages in various applications. Finally, we demonstrate several mobile applications which leverage these systems to create novel mobile interactions.