A method and apparatus for customizing tool paths. A reference tool path is identified for a tool based on an expected shape for a surface of an object. Offset data is generated for a plurality of sample points identified for use in evaluating the surface of the object. The offset data identifies a difference between the expected shape for the surface of the object and an actual shape of the surface of the object. The reference tool path is modified using the offset data to form a modified tool path for the tool.