The present invention concerns a mould divided into three parts for the direct moulding of a membrane equipped with a series of suction cups having the particular shape of an open hourglass or of bellows or of a cylinder onto a support made of breathable, waterproof or hydrophilic material positioned on the intermediate mobile part of the mould which is pressed against the lower part of the mould during the moulding phase and raised after moulding has been completed thanks to a series of springs that bring it back to its original position permitting automatic removal of the moulded suction cups without damage to their particular shape.