A method of operating a static mixer for fluid media comprising the steps of providing a flat, structural element including a plurality of separate, adjoining strips of a sheet material, each strip having first and second, spaced-apart longitudinal edges, the longitudinal edges of adjoining strips being placed opposite each other, the adjoining strips being in contact with and secured to each other where they contact each other to provide the flat structural element with structural stability, the longitudinal edges of the strips including a plurality of repetitively spaced-apart recesses of a predetermined shape, and the recesses in longitudinal edges being opposite each other to define a multiplicity of repetitively arranged openings distributed over the structural element, folding at least some of the structural elements along fold lines to give the folded structural elements a zigzag shape in a cross-section transverse to the fold lines, assembling the folded structural elements into layers to thereby form a packing, installing the packing in the exchange column, and flowing first and second fluid media over the packing.