A method for modifying a computer-aided design model of a three-dimensional object, the method comprising establishing a threshold wall width, providing at least one sliced layer polyline of the computer-aided design model, determining a first distance between first and second portions of the at least one sliced layer polyline, and adjusting locations of the first and second portion to provide a second distance if the first distance is less than the threshold wall width, where the second distance is about equal to the threshold wall width, or greater.