Abstract: A unitary composite corrugated board structure of a double layer of single-faced corrugated board is fabricated by assembling the boards with their corrugated faces in nesting contact and then compressively cutting the layers by applying a force in a direction substantially perpendicular to the surface of the planar lining sheet of the board. The cutting operation crushes the corrugations at the cut edge into interlocking reentrant configurations which hold the boards together without the need for an adhesive.