This geometry nodes setup creates procedural goop along the boundary of boolean operations. When subtracting shapes from an object, the system automatically places the goop effect onto the newly created faces. By inverting the normals of the cutter objects and enabling the included material transition node, users can generate a visual transition between two distinct materials with the goop positioned precisely in the middle. The provided project file includes two example scenes demonstrating both the standard boundary goop and the material transition effect.