The author presents a user interaction methodology based on a six degree of freedom interactive input device called the Spaceball. This methodology is geared for computer graphics applications that require items to be positioned or displaced in three-dimensional space in a purely visual and esthetic fashion. When the Spaceball device is used in conjunction with a common 2-D mouse-the Spaceball device held in one hand and the mouse in other-overall visual depth perception on traditional 2-D displays can be considerably enhanced by exploiting a technique called motion parallax, thereby promoting full three-dimensional user interaction. This paper focusses on the application of this methodology to sculpting highly irregular polygon mesh surfaces, such as character faces or any other surfaces of arbitrary shape. The Spaceball device is used to move the object being sculpted while the mouse carries out the picking and deformation work, all of which is projected onto the screen in real time. As case studies, three common operations in polygon mesh sculpting are described in detail (vertex creation, primitive selection and local surface deformations)