Abstract: The aim of the invention is to shape a flat web material (12) into a constant three-dimensional structure with a plurality of folds along differently oriented folding lines and with elevations and depressions. This is achieved in that the flat web material is inserted between a lower holding die (20b) and an upper holding die (20a), which are largely flat, consist of a flat material, and have pre-shaped bending lines that lie over one another in a precise manner when lying against the flat web material. A lower (30b) and an upper molding die (30a) are then guided thereto and brought into position, said molding dies consisting of a flat material with specified folding lines which oppose one another in a precise manner.