Abstract: A deck for a rotary lawn mower is disclosed which is designed to be fabricated from a polymeric composition by a blow mold process thereby forming double walls. The cavity between the double walls is filled with a suitable foam for added rigidity and sound absorption. The deck includes a support for an engine which defines an opening in the deck for the output shaft of the engine to extend through to the bottom of the mower, a tunnel for directing the grass clippings having a discharge opening for the clippings, and mounting platforms for the mower wheels and handle are integrally formed therewith in a single forming operation.