A mold block includes a tool body with a contoured finished surface adapted to receive a tool insert having a forming surface for forming a bottle neck in a molding operation. The tool body defines an internal channel for heat transfer with the forming surface. At least a portion of the channel is offset generally equidistant from the finished surface to provide a path contoured for conformal cooling of the insert. The tool body has a pair of ports intersecting the channel. Several methods for forming a mold block are disclosed and include machining a contoured finished surface adapted to receive a tool insert on a tool body, forming a heat transfer channel within the tool body, and forming a pair of ports into the tool body. At least a portion of the channel is offset generally equidistant from the finished surface for conformal cooling of the insert.