1. A drawing system, comprising: a computer system having a display and a pen input device having a pen stylus; the computer system having curve model generation software running thereon; the curve model generation software responsive to one or more strokes of made with the pen stylus to sketch a first 2D curve and generating a first 2D vector curve therefrom; the curve model generation software displaying a guide on the display to guide the user in sketching a second curve; the curve model generation software responsive to one or more strokes made by the user with the pen stylus to sketch a second 2D curve and generating a second 2D vector curve therefrom; and the curve model generation software generating a pair of mirror symmetric 3D vector curves from the first and second 2D vector curves which are displayed on a canvas displayed on the display.