An electroformed tool has an integrated base with channels contacting the tool with heat exchange fluids flowing through the channels during molding or embossing. A blank base is machined with a network of interconnected open channels on a top surface and end flow through passageways communicating with the channels. The tool is used as an electrode to erode the top surface of the blank base using plunge electro discharge machining by lowering the uneven deposit on the bottom of the electroformed tool down onto the top surface of the blank base in the electro discharge machining environment to form a top contoured surface to mate with the uneven deposit on the non-molding side of the substrate. Thermal management fluid channels are thereby conformal to the mold cavity. The tool and base are sealed together.