A disk drive includes a disk drive base, a disk rotatably coupled to the disk drive base having a disk surface, a head stack assembly rotatably coupled to the disk drive base adjacent the disk surface, and a cover attached to the disk drive base enclosing the disk and head stack assembly there between. The cover includes a metal layer and a polymer layer substantially coextensive with the metal layer and extending substantially across the disk drive base. The polymer layer includes a polymer layer feature extending away from the metal layer towards the disk drive base. The polymer layer feature defines a cavity between the polymer layer and the metal layer.