Abstract: The invention relates to a press knife for cutting sheet material, comprising a continuous length of blade (2) in the shape of a desired outline to be cut in sheet material and having at least one continuous cutting edge (4) and preferably two, said knife also having at least one elongate reinforcing member (6) extending transversely of the knife and linking one portion of the blade with a generally oppositely disposed portion. The knife is provided with two support plates (8) shaped to fit within the perimeter of the continuous blade (2) and arranged so that the reinforcing member (6) lies between the plates (8), and at least one making strip (4) received in a slot (12) of one plate (8) and in a congruently disposed slot (12) in the second plate so as to bridge the two plates and retain them in position with respect to the blade.