What would be cooler would be a completely separate bond-building robot that can weld / whatever and can independently traverse the completed building. When it

What would be cooler would be a completely separate bond-building robot that can weld / whatever and can independently traverse the completed building. When it was too far from its next destination a quadrotor would come and give it a lift. You might have several different types of crawler. A couple to receive materials from the quadrotor and hold them in place while a third follows a weld pattern.