a molding machine for dispensing at least two materials which , when combined , foam and cure within a mold thereby to form a plastic article . the dispensing is accomplished by displacing measured amounts of hydraulic fluid to a pair of chambers within each of which there is located a stainless steel bellows that is supplied with the respective material from a source thereof under pressure . when the displaced hydraulic fluid causes the bellows to collapse , the materials in the bellows are displaced therefrom into a mixing chamber in the form of high velocity jets and are mixed therein and the mixture is forced from the mixing chamber to the mold cavity to be filled . the bellows are then permitted to expand under the pressure of the material supplied thereto and the machine is ready for a further molding cycle .