Stepped surface

I asked last week how to get raised text or shapes protruding from a curved surface and I got some excellent replies. Now I find What I need is to "step" the offset surface to different elevations. To explain, let's say that the original curve is a sphere and the first offset shape is a rectangle. This produces a rectangle shape offset from the sphere by a specified height. The surface of the rectangle is curved to match the sphere. Which is what I need but I also need to "step" this curved surface. I can do this to some extent by offsetting (expand) the rectangle surface with a smaller SQUARE (or other) shape. But the square must be completely inside the perimeter of the rectangle or it fails. And I need to step right from, at least, one of the edges. If it touches or overlaps an edge, it fails. Is there a method to do this. Thanks Peter