In Alias there are several basic primitives such as spheres, cubes, cones etc. There attributes are defined in a modal dialog box, and then a shape is created when the user clicks on the screen. A transform manipulator is provided after creation to allow for scaling, rotation and position transformation.
Other packages allow the user to click and drag to specify values such as length, width, height, and circumference, allowing the user to define these attributes as the shape is created rather than afterward.
Would it be useful to change the workflow for creating primitive shapes?