We didn’t notice [Nikita]’s post about building a concrete 3D printer, a few months ago, but the idea seems sound: build a basic CNC XY axis and then add a mortar pump and hose to deposit concrete.

Computer Numeric Control technology has been around for a long time. It’s at the heart of our 3D printers, laser cutters / etchers and CNC milling machines. They all work the same way — you begin with ...