An apparatus for etching a pattern in an etching zone laid out on a substrate includes a pen that can be freely moved manually relative to the etching zone, the pen being equipped with an etching head able to etch the substrate at an etching point when etching is triggered, a measuring unit for measuring position and orientation of the etching head relative to the substrate, a control unit configured to calculate coordinates of the etching point as a function of the measured position and orientation of the etching head relative to the substrate, to trigger etching at the etching point if the calculated coordinates of the etching point correspond to coordinates of a point to be etched, the coordinates of the point to be etched being encoded in a prerecorded drawing of the pattern, and to automatically prevent etching otherwise.