just as you could hook up a pen to a plotting machine ( http://www.niklasroy.com/project/149/cardboard_plotter http://www.niklasroy.com/project/149/cardboard_pl

just as you could hook up a pen to a plotting machine ( http://www.niklasroy.com/project/149/cardboard_plotter http://www.niklasroy.com/project/149/cardboard_plotter ) and use it as a printer, you could hook this up to (e.g. lego mindstorms, arduino, whatever) and implement a 3D printer. Arguably, humans are also (rather overspec'd) plotting machines.