Abstract To produce a panel of variable thickness, a stratified assembly of a layer of fibers containing a non-polymerized binder and at least one cover sheet is placed between the mold and mold-backing of a molding press. The stratified assembly is caused to conform to the interior surface of the mold or mold-backing by forcing the cover sheet against the mold or mold-backing interior. Hot air is blown into the fiber layer from the mold surface opposite the cover sheet, into at least the region that will correspond to the area of greater thickness. The direction of the heated air is reversed after a period of time, the blowing of the air being maintained and adjusted in order to secure polymerization of the binder. At the same time, the portions of the panel corresponding to areas of lesser thickness, generally the edges of an acoustical panel, are cured (the binder polymerized) by contact heating means. To effect cross-over blowing, both the mold and mold-backing are provided with ports through which heated air may be blown or passed.