Much more interesting to think about is what you can do that exploits the properties of this. The two big ones seems to be insane speed and curved surfaces. Could this be used to rapidly build bunkers or bridges in a war? How about rome style aquaducts to channel water from a flood or even to simply build dikes in an emergency? Maybe the speed would maybe make previous expensive projects cheap such as massive water irrigation projects. Could printing curved surfaces let you print temporary dam's?

Edit: or how about printing your very own pyramid or a road?