Wound warps are made by pulling a multiplicity of warp filaments off respective supplies and winding them around a warp beam by rotating the warp beam while pressing the filaments against the beam with a predetermined packing force by a packing roller. A first pair of ports has openings located on a first face of the housing, and a second pair of ports has openings located on a second face of the housing, wherein the first face is opposite the second face. A passfail signal is communicated to a visual indicating device, such as an LED, on the wafer. In the following the etching depth At is increased by anisotropic etching in one process with alternatingly successively following etching and polymerization steps, such that the mask under etching u remains constant and such that the etching front of the etching profile obtains a new course, wherein the side walls of the structure are covered with a polymer.