In the following images, the brown surfaces are either Open Inventor primitives or are parametrically derived. The orange surfaces are the box spline zero set.
The figure on the left is simply the box spline zero set for a cyclide. The figure on the right shows the blending of two cyclides at one of their intersection points.
The figure at the upper left shows the intersection of three cylinders and a sphere represented by Open Inventor primitives. The figure at the lower shows the box within which we re-represent the CSG objects in box spline format. At the lower right is the box spline zero set surface itself, and at the upper right are the CSG objects with the box spline zero set blend.