Abstract: An apparatus for sequentially forming folds in a sheet of paper which is continuously moving substantially in a single plane. A first fold is formed in the center of the continuously-moving sheet of paper and subsequent pairs of folds are sequentially formed, one on each side of the previously-formed folds, until the entire continuously-moving sheet is folded. Guide wires retain each folded section until the entire sheet is folded by the cyclic upward movement of a continuous flexible wire loop held for free movement on a pair of spaced apart pulley assemblies. Each pulley assembly includes a plurality of evenly spaced pulleys each of which are held for free rotation on a support frame. Each support frame is driven in rotation about a central axis of rotation. Each individual pulley includes a freely rotatable ring surrounding the periphery of the pulley around which the flexible wire loop is held.