He used the new material of Plexiglas—first introduced to the United States in sheet form in 1934—for his hybrids of painting and sculpture that he called Space Modulators. The reflective and transparent qualities of the material served his desire to modulate and activate light in order to create the impression of motion and movement, often in unexpected ways. At times, he achieved extraordinary effects using sheets of flawed Plexiglas. During the manufacturing process, overheating of the plastic can cause bubbles, tide lines, and other imperfections to form on its surface. The defective sheets that Moholy-Nagy used may have been factory discards that were embraced by the artist due to the difficulty of obtaining materials like Plexiglas, which were needed for the war effort. Moholy-Nagy favoured the flawed sheets and accentuated their ability to cast shadows, exploiting the distortions they created and generating vibrating effects and a sense of movement.