A unitized heat conductive assembly 32 formed of a one piece heat conductive conduit 40 which permits shaping the heat conductive assembly as a continuous unit. The heat conductive assembly 32 is press fit into the heater block 12 configured so that it provides a predetermined flow path 14 for the flowable molten plastic materials to be delivered to the injector nozzles. There is provided a heat flow path 28 that follows the flow path 14. The heat conductive carrying conduit 40 is formed with an opening 42. The conductive conduit 40 is formed from a tubular piece of conductive metal such as copper or brass by a swaging process which forms a tubular structure 40 in a continuous length. The outer contour of the tubular structure 40 can be round or oral and the preferred shape is either square or rectangular. The cross-section the heat conductive conduit 40 has a dimension W transverse the cross-section and a narrower dimension N at the bottom of the cross-section so that it is adapted to be press fit into the channel 30. A channel 30 is provided have a dimension W transverse the channel mouth 52 and a narrow dimension N.sup.1 at the bottom. The heat conductive conduit 40 forms a press fit within the channel 30. The continuous length of heat conductive conduit 40 is shaped to follow the flow path 14 of the molten plastic material flowing through the manifold 10.