In addition to his Emmy and Grammy Award winning compositions, Williams dabbled in conceptual art. In the late 1960s Mason produced a work titled Bus, a life-sized (11'x37'), photographic poster of a Greyhound Bus. It's included in the permanent collection of New York's Museum of Modern Art. He also created an aerial sunflower: for a short film, he had an biplane skywrite the stem and leaves of a sunflower in the sky beneath the sun, the sun itself became the blossoming flower to viewers on the ground at the appropriate angle).