Abstract: Method and arrangement for manufacturing a hollow elongate construction element in which a first blank and a second blank (1, 14) are conveyed through a furnace (2) for heating to working temperature and are conveyed between rolls (3, 4) with profiled surfaces for preshaping in one or more steps. The blanks are each conveyed through a forging press with a number of interacting die cushions, the blank being worked in a number of steps (5, 8, 11) to form halves of an in the main finished product, having a cross section essentially in the form of a U-profile with a predetermined varying height, width and material thickness along its length. The second blank (14) constitutes in the main a copy of the first blank (1). In a final step (15), the blanks are joined together to form a composite hollow construction element (18).