A method and appertaining system provide for automatically adding a wax guard to a hearing aid shell impression. The location of a canal, tip of the canal, and central line of the impression are automatically identified in a digital 3D representation of a hearing aid shell impression. A first wax guard plane is determined at a predefined flip distance from the canal tip along the central line, and a second wax guard plane is determined at a predefined canal tip offset distance from the canal tip along the central line. A size and position for a feature of the wax guard is calculated based on predefined parameters, and the wax guard is constructed utilizing the calculated side and position. The type of wax guard can be a bell bore design, an open design, a Philip design, or a flip design.