Abstract: Two or more flat sheets of flexible material, at least one of which is transparent, are driven concurrently endwise along a path by successive advances at the same rate of travel while they are juxtaposed in direct face to face contact with each other. At one location along the path the sheets as a unit are pleated, heated, and pressed into a series of parallel, substantially identical flat pleats, with the pleats of each sheet interfitting corresponding pleats of the other sheet, and each pleat being partially overlapped by, and partially overlapping, those adjacent pleats of the same sheet between which it is positioned. While the sheets are held in flat pleated condition, they are cooled to set the pleats, and then are coated concurrently over the outwardly exposed face portions of their plates with light reflecting or decorative paint or flowable film forming material. The coating is then dried.