An accumulation extruder head comprises a head body (10) which has an accumulation chamber (13a) with a vertical axis, designed to be filled with a load of thermoplastic resin, and a bottom outlet mouth (11) for expulsion of the load of thermoplastic resin in the form of a tubular parison. A piston (18) is coaxially inserted inside the accumulation chamber (13a) and is movable in a reciprocating manner inside the accumulation chamber along the vertical axis in an expulsion direction and an upward direction. A mechatronic assembly (30) comprises an output element (31), which is linearly displaceable along the vertical axis between a raised position and a lowered position, and a plurality of electric actuators, each able to rotationally drive a respective rotating element coupled to the output element (31) so as to displace the output element in the vertical direction. The output element (31) cooperates with a pusher assembly (40), which is rigidly coupled to the piston (18) for displacement therewith so as to push the piston (18) in the expulsion direction.

A system for blow-molding a three-dimensional part or article. The system comprises at least one regrind extruder system and at least one color extruder system, a forming system for forming a blank from the viscous mixtures released by the extruder systems and a blow mold configured to receive the blank. The blank has a layered configuration characterized by a number of layers across a cross-section of the blank. Each one of the layers is formed by one of the viscous mixtures released by the extruder systems. The blank is inflated inside the blow mold to form the three-dimensional part or article. The three-dimensional part or article retains the layered structure of the blank.