Abstract: An electrode mask for electrowinning a metal is provided. An example technique forms openings in a solid nonconductive sheet, such as vinyl, polyvinyl chloride (PVC), or other plastic and adheres the sheet as a solid to a cathode surface as a mask. The mask protects the cathode surface from electrical interaction with an electrolyte, while the openings allow controlled electrodeposition of a metal in harvestable rounds, which can be stripped from the cathode. The electrode mask is reusable, and easily removed for recycling and replacement. A matrix design engine calculates pattern and sizes for the openings in the mask to optimize electrodeposition of the metal based on multiple parameters including the metal to be deposited, ions present in an electrolyte, electrolyte concentration, pH level, voltage, electrical current density, solution temperature, electrode temperature, or plating time.