Scenic design sketch of one of the three great velour portals created for the 1937 Federal Theatre Project 891 production The Cradle Will Rock at Maxine Elliott's Theatre

• Producer John Houseman, Run-through (1972):
  For America's first proletarian musical, Orson [Welles] had devised an extravagant scenic scheme that called for a triple row of three-dimensional velour portals between which narrow glass-bottomed fluorescent platforms, loaded with scenery and props, slid smoothly past each other as the scene shifted back and forth from the night court to a street corner, a church, a drugstore, a hotel lobby, a faculty room, a doctor's office and the front lawn of the finest house in Steeltown U.S.A. [page 248]
  By the end of May our three great portals were in place and our illuminated glass-bottomed floats were cruising across the stage, pursued by panting players, trailing yards of black writhing cable in their wake. [page 254]