Abstract: The apparatus comprises a foaming cylinder containing a foaming chamber into which a liquid foaming agent is discharged through a small orifice. The chamber is closed at one end by three, aligned discs having therethrough a plurality of axially extending openings which connect the foaming chamber to a venturi. Compressed air, which also enters the foaming chamber with the foaming agent, forces the liquid through the openings in the discs to the venturi section. The openings in the center disc are angularly offset from the openings in the two outer discs, so that the discs form a maze through which the foamed liquid passes from the foaming chamber to the venturi. The venturi feeds the foamed liquid to a mixing chamber into which a resin is introduced under pressure through a spinner and orifice so that the foamed liquid is completely mixed with the resin before being discharged as a foamed plastic.