An improved core is adapted to extend axially through the central portion of a mold cavity in which an airfoil or other article is formed. The core is used to form cooling passages as the airfoil is cast in the mold cavity. The core has an elongated cantilevered center section which is disposed within a main or base section. A metallic pin member extends from a free end portion of the cantilevered center section of the core to the main section of the core to hold the free end portion of the cantilevered center section against movement relative to the main section.