Methods and structures. A planarization method includes: providing a contact structure, where the contact structure includes an axle configured to rotate about an axis of rotation, a plurality of cantilever arms, each arm having a first end connected to the axle, where each arm extends radially outward from the axle; and a plurality of electrically conductive spheres, where at least one sphere is disposed on a second end of each arm; placing a substrate in contact with the spheres, applying an electric voltage to the axle, where the voltage transfers to the substrate, where responsive to the transfer an electrochemical reaction occurs on the substrate; rotating the axle, wherein the spheres revolve about the axis, wherein at least one sphere remains in electrical contact with the substrate; and electrochemical-mechanically planarizing the substrate. Also included is a contact structure, an electrical contact, and an electrical contact method.