Both Perspex and Plexiglas were commercialized in the late 1930s. Instead modern materials like plastic laminates, aluminium and Perspex were used. Against the blue background, the metallic lettering now has the appearance of glass or perspex. It has been encased in a Perspex casing. The car had a lifting rear door, and sported then unusual curved perspex roof panels. The cell is fabricated out of perspex or glass. In 1938 perspex (polymethylmethacrylate (PMMA)) began to replace glass in contact lens manufacture. The doors had no external handles or locks and the windows were sliding Perspex side-screens. It had a glow in the dark cover and came in an engraved Perspex slipcase. The clapperboard combines a 'chalkboard slate' or perspex board with 'filmsticks' or 'clappersticks'. The passenger was able to view the outside through a perspex dome. The passenger would be able to view the outside through a Perspex dome. It was put back on display behind Perspex and guarded by security men. It was manufactured primarily from clear Perspex. However, they were prevented from soiling the sculpture directly by its Perspex case.