Abstract : One of the major problems in geometric modeling is the control of shape construction. Indeed, one should be able to construct geometrical forms by combining or manipulating simple entities. This problem is even more important when we deal with fractal geometry. In this paper, we propose some methods for increasing the modeling capabilities of fractal shape constructions. We propose two extensions of the IFS model. The first is based on the integration of free form techniques in an IFS formalism, while the second deals with the definition of matrix of attractors to give a constructive approach of fractal shapes.