a factory worker feeds flat cardboard sheets into a large corrugating machine with visible rollers. The machine transforms the smooth material as it passes through the mechanical rollers. The flat cardboard emerges on the other side with distinct parallel ridges and furrows running across its surface. Another worker catches the newly corrugated sheets which now have the characteristic wavy pattern. The supervisor points approvingly at the perfectly formed ridges and valleys in the material. flat material being formed into folds, ridges, and furrows through the corrugating process