selecting pieces of terrain for blueprints

[NETILIORSAMH]

so imagine. you finished a blueprint but its on a mountain or something or its in a cave or underground. don't worry because now we can actually import custom terrain into our builds. not sure on what to do for caves yet but I was thinking drawing a circle around your blueprint once it has been selected itself and in that circle you can actually save terrain and it essentially will be cut out and saved along with your blueprint so they are together.