A method, apparatus, media and signals for producing a representation of a mold for forming an appliance for a living body is disclosed. The method involves identifying points representing a line corresponding to an intended edge of the appliance on a surface of the mold, the surface being defined by an input plurality of points representing a general shape of the mold. The method also involves identifying regions extending along the surface on opposite sides of the line, adjusting at least one coordinate of at least one of the input plurality of points that falls within at least one of the regions to alter the shape of the surface in the at least one region to produce a modified surface representation, and storing the modified surface representation in a computer memory to produce a modified representation of the mold.
