Wow that is impressive - I wonder how hard it would be to get them all to synchronise..

What I think would be the really hard part is avoiding the collision of the heads. I mean, what if your object is 1 meter long. You are printing the thing across with all the heads - there will surely be sections in between each print head that would be left out or one of the heads would need to take control of "it's side of the fence" if you get my meaning, so two of the heads are not printing so close that they collide.. I'm guessing maybe they all print over eachother? man this is mind boggling...