A method and apparatus for forming patterns on sheet material are disclosed. The method comprises a continuous lateral stretch process for producing zero- or near zero-curvature structures. In a preferred embodiment, the method comprises pre-gathering the sheet material in the lateral direction to form longitudinal corrugated folds and then feeding the corrugated material through one or more sets of oscillating formers, preferably articulating discs, to impart folding in the lateral direction. Optionally, the sheet material may be fed through one or more sets of patterned rollers.