In the fabrication of an electronic circuit incorporating an insulating substrate where there is a need for an aperture through the substrate, there arises a problem of how to create the aperture. If a round aperture is desired or acceptable, and if the substrate is of relatively soft material, the aperture may be simply drilled through the substrate or the aperture may be punched through the substrate. Where, however, the aperture must be of another shape, rectangular, for example, or where the substrate is brittle and/or abrasive, other measures must be utilized.