A pen-based system allow users, such as artists, graphic designers sand illustrators, and the like, to create accurate curve models by sketching. A tool set implemented in software that runs on a computer system combines paper sketch metaphors and a minimalist gesture set. This tool set provides an environment where the artists can focus on the creative task at hand rather than the details of operating software. A pen-based drawing method and system allows users to create and edit three dimensional (“3D”) objects by sketching.