Metal-coated polymers shaped by 3D stereolithography are introduced as a new manufacturing method for passive components for millimeter to terahertz electromagnetic waves. This concept offers increased design capabilities and flexibilities while shortening the manufacturing process of complex shapes, e. g., corrugated horns, mirrors, etc. Tests at 92.5, 140, and 170 GHz are reported. (C) 2012 American Institute of Physics.