A technique of building 3D models from an iso-surface in a scalar field is discussed. One of the characteristics of this method - referred as the soft object of implicit surface method - is that a few primitives blend to form a complex surface. The shape of these primitives is given by a field function. A new family of field functions is introduced which have to be more useful for modelling than previous field functions. It is shown that the new field functions are useful for modelling and some of the problems appearing in using this technique are examined: primitive shape, undesirable blending and under sampling effects. The use of several field functions simultaneously and the manner in which the soft object system has been integrated into an animation system are also discussed. Further investigation domains are also mentioned.