For controlling a physical dimension of a solid state structural feature, a solid state structure is provided, having a surface and having a structural feature. The structure is exposed to a first periodic flux of ions having a first exposure duty cycle characterized by a first ion exposure duration and a first nonexposure duration for the first duty cycle, and then at a second periodic flux of ions having a second exposure duty cycle characterized by a second ion exposure duration and a second nonexposure duration that is greater than the first nonexposure duration, for the second duty cycle, to cause transport, within the structure including the structure surface, of material of the structure to the structural feature in response to the ion flux exposure to change at least one physical dimension of the feature substantially by locally adding material of the structure to the feature.