> CNC machines and 3D printers Those are very controlled environments. Outside where there is weather and wind, anything can happen. Also if there is a bug in

> CNC machines and 3D printers Those are very controlled environments. Outside where there is weather and wind, anything can happen. Also if there is a bug in the software or some hardware fails in a CNC machine then you loose some material, not a big of a deal. If the concrete tower collapses you loose a skyscraper volume full of concrete, also it takes days or weeks to clean the area up.