Abstract: A method of treating the surface of a 3D object, comprising obtaining a digital 3D shape representation defining characteristics of the object; using a computerised device to convert the 3D shape representation into a digital 2D shape representation defining the 3D surface of the object as it if laid out flat; using the computerised device to generate a digital 2D tool path representation defining movements an applicator or removal tool would take to treat the surface of the shape defined by the 2D shape representation; using the computerised device to convert the 2D tool path representation to a digital 3D tool path representation defining movements that the applicator or removal tool will take to deposit material on, or remove it from, the surface to treat the 3D object; and using the 3D tool path representation to control the applicator tool or removal tool to treat the 3D object.