Intersect Shapes Request
I saw that there is already an Idea for this, but I wanted to quickly share my issue for intersecting shapes. For context, I just started a hobby project trying to replicate the Dubai Fountain, and to use some deconstructed kitbash architecture features that I want to rebuild into new buildings with procedural model.
I can import the fountain shape from OSM. I decided to build a round platform stretching out just beyond my intended view distance since I don't think I can "stamp" the terrain layer vertically enough for a detailed inset feature like a fountain/pool. I set them both to ground plane with all vertices at y = 0. However, I cannot use the subtract shapes tool without creating a polygon sliver that stretches out to the circles edge. Although, that did allow me to intersect the shapes in a manner. But this will become VERY problematic if I try to add more swimming pools, lakes, and other inset features. 
To make this matter more confusing, it looks like I can draw intersecting shapes using polygonal shape drawing tool - squares, circles and sometimes mildly complex polygons that do intersect. But, when I try to separate the inset shape using the shape separate tool, it reverts back to a single plane and creates a second object instead of keeping the hole, which means I can't use the inset shape to apply new code (perhaps a negative extrusion or flipped roof plane for a swimming pool.
I suppose everything could be built from the ground up without holes/donuts, by thinking forward and extruding all polygons up from base, but that is a much harder place to start your design thinking when working with OSM data.
Also, I tried exporting the shape to ArcGIS Pro, but I had issues with figuring out how to create and edit the shapes there too.
Any ideas, explanations, work-arounds, or possible future features to help with this? Thanks!
So I did manage to work around this. And this post became kind of a blog.
My original subtract shape "inlet" (shown in post above), provided a shape to build off for future holes in the platform. You can see two more holes in the "platform" created by using the polygonal drawing tool. They create the "shape bridge" to the next holes. You can then use the separate faces in this method. And then reapply the start shape code as necessary.
Platform holes created by working with "connector" shapes.
Separating the face
Using the amazing ESRI fence creation code... It has an occlusion test which blocked the fences at the raised platform. My platform is raised to .89 offset of y=0, so fence must be raised to .895 to pass fence code occlusion.
Fence around fountains fixed.
Working toward a complete scene.
