an electrode mask for electrowinning a metal is provided . an example technique forms openings in a solid nonconductive sheet , such as vinyl , polyvinyl chloride , 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 .