Abstract: The installation comprises a rectangular, parallelepipedal, leaktight steam chamber (1) provided with a gate (2) on one of the short sides, inside which a tubular fixed mold (4) of perforated steel plate is attached at a distance from the walls of the chamber, the shape of the mold corresponding to the external shape of the panel to be obtained. A first set of fixed, parallel, perforated metal tubes (5), inside the mold (4), possesses lateral holes (9) for the passage of a second set of perforated or non-perforated metal tubes (10) firmly fixed to a movable external support (11), passing through one of the short walls of the steam chamber (1) and capable of moving perpendicular to the tubes (5) of the first set, passing through the latter. The chamber (1) is provided with inlet valves (13) for the partially expanded synthetic material, an inlet (14) for steam and an inlet (15) for a cooling fluid.