Structural Foam Moulding is used to produce bulky items overcoming warping, cracking, shrinkage and much of the built-in-stress found in conventionally moulded thick components. The surface aesthetic imperfections associated with structural foam moulding often require a finishing operation by painting, laquer spraying, dipping, veneering or covering with fabric materials unless these surface imperfections are exploited to obtain a wood-like effect trough colouring process. The "piggy back" injection system extensively used by Presma is the perfect touch in structural foam. A preset quantity of material is extruded into two punching cylinders under subsequently injected directly into the cavities of the mould through two or more nozzles.