In some examples, a method includes forming a photoresist layer on a surface of a metallic substrate and developing the photoresist layer to define a pattern exposing a portion of the surface of the metallic substrate. The method also may include forming an electrically conductive layer on a surface of the photoresist layer and the exposed portions of the surface of the metallic substrate. The electrically conductive layer contacts the exposed portions of the surface of the metallic substrate. The method may further include submerging the substrate, the photoresist layer, and the electrically conductive layer in an electrolyte solution; and applying a voltage to between a cathode and an anode submerged in the electrolyte solution to anisotropically etch the metallic substrate where the electrically conductive layer contacts the exposed portions of the surface of the metallic substrate to form at least one feature in the metallic substrate.