Abstract: An electronic core for a metal card, such as a transaction card, having a metal core and a cured polymer top surface, is manufactured by a process in which a two-part polymer mixture is introduced to a reservoir holding the metal core in a process chamber, and then a partial vacuum followed by pressurization with inert gas are used to reduce the volume of voids in the partially-cured polymer mixture, followed by curing outside of the process chamber, and then the top surface is removed by a treatment operation, such as milling or etching, to form a reduced upper surface with less surface irregularities which is more substantially plan the original top surface.