Abstract: A three-dimensional object modeling tool is described that can derive the 2D cross sections of one or more lofted or unlofted surfaces, allowing those surfaces to be modified instantly. The modeling tool (loft tool) includes sub-tools for selecting a surface, moving a 2D section, editing a 2D section, creating a 2D section, and removing a 2D section. By analysis of the selected lofted surface and its faces, the loft tool can derive an appropriate number of 2D cross section to present to the user for manipulation. When deriving the 2D cross section the modeling tool operates by simplifying the curves making up the lofted surface, and from these can generate 2D cross section that can be easily manipulated and used to instantly update the lofted surface and redisplay it for further user modification.