I mean, the novel of 3d printing is that it's just additive construction, don't we already build dams and almost all other structures that way already?

A crane is just a bigger print arm :)

Yes, but the dream is to build physical things, just with software.

You type in your commands and then magic happens and something is build (after a while). Nothing to be done by hand (ideally)

But I would love to play with a fully automated remote controlled printer the size of an crane, though.

But then there should probably be no humans around.

You have a point :)

Those beaver-bots will be ferocious!