STL files are used for renders and 3d printing, and many times people publish stl files online, but they can't be easily modified without manually reverse engineering it. This tool would be able to intelligently produce a parameterized 3d-model from a static 3d-model.
This shape, saved as an STL file looks like a set of triangles creating a surface. No conventional software can read this as a circle.
The same shape is made by drawing a sketch and revolving it around the line in the center. It is a smooth shape defined not as a list of coordinates, but as an equation.