1. A computer-implemented method performed by a computer for performing three-dimensional (3D) modeling comprising: (a) activating, in a 3D modeling application executing on a multi-touch device, a modeling tool; (b) receiving an input touch event; (c) determining that the input touch event triggers creation of a new 3D geometric form instead of another operation; (d) receiving an input gesture on the multi-touch device, wherein the input gesture comprises a drag of a user's finger along a path; and (e) dynamically, in real-time as the input gesture is received, creating and displaying the new 3D geometric form, wherein a shape of the new 3D geometric form corresponds to the input gesture.