A method of forming a headrest assembly includes providing a first mold that encloses a first cavity in a closed condition. A support is positioned in the first cavity. A first material is blow molded into the first cavity and around a portion of the support to form a core part. The core part and support are removed from the first mold. A second mold encloses a second cavity in a closed condition. The core part and the support are placed into the second mold in an open condition. A fluid is injected into the core part through the support. The second mold is converted to the closed condition. A second material is injection molded into the second cavity and around the core part to form an outer shell around the core part. A fluid is withdrawn from the core part through the support.