Plasterboard panels (A,B) formed by layers of cardboard (1,3) with a sandwiched plaster sheet (2) and by layers of cardboard (4,6) with a further sandwiched plaster sheet (5), are clamped between a female half mold part (C) and a male half mold part (D) of a forming press, are spread with vinyl adhesive or other suitable water-based adhesive at the layers of cardboard (3,4). In each one of the two panels, the plaster sheet (2,5) is fractured radially and the layer of cardboard (3) on the outside of the curvature is stretched and the layer (4) on the inside is compressed. The bonding of the layer of cardboard (3) of the first panel (A) to the layer of cardboard (4) of the second panel (B) forces the two panels to a permanent, stable, equilibrium of the respective opposite curving tensions.