A system and appertaining algorithm provide a cutting and shaping of the hearing aid shell using an Ellipsoidal Line Cut that increases the speed of detailing operations and enables a creation of more cosmetically appealing shells. A contour algorithm determines a projected contour on the bottom cut plane that corresponds in shape to a portion of the line cut plane contour, and a merger algorithm defines a line cut surface between the portion of the line cut plane contour and the projected contour. An elimination algorithm eliminates parts of the new hearing aid shell design that extend beyond boundaries defined by the original hearing aid shell design.