This paper presents an object-oriented framework which enhances the collaboration of three categories of experts that play fundamental role in the development of a software for interactive 3D geometric modelers. It aims at three purposes. First, it supports application developers to build a graphics interface for manipulating with 2D devices their own 3D data representations, without intimate knowledge of its internal structure. Second, it provides facilities for interface researchers to create and experiment 3D widgets from reusable draggers and 2D-3D mapping strategies. Finally, it permits graphics experts to implement sophisticated draggers and complex 2D-3D mapping strategies by overriding operations of the predefined abstract classes.