Today’s user interfaces for most 3D graphics applications still depend heavily on 2D GUIs and keyboard input. There have been several recent attempts both to extend these user interfaces into 3D and to describe intermediary 3D widgets1 that control application objects [3; 4; 5; 7; 13; 15]. Even though this style of interaction is a straightforward extension of interaction through intermediary 2D widgets such as dials or sliders, we know of no efforts to develop interactive 3D toolkits akin to UIMX or Garnet [11]. The Brown Graphics Group has had considerable experience using its Unified Graphics Architecture (UGA) system [16] to script 3D widgets such as deformation racks [14], interactive shadows [9], parameterized models, and other constrained 3D geometries. Using this experience, we have developed an interactive toolkit to facilitate the visual programming of the geometry and behavior of such interactive models. The toolkit provides both a core set of 3D widget primitives for constructing interactive behaviors based on constrained affine transformations, and an interactive 3D interface for combining these primitives into more complex widgets.