I don't know if you're thinking of giant Makerbots or what. In the late seventies I attended a conference at Princeton that was about putting space colonies at the Lagrange points. specifically L5. See - http://en.wikipedia.org/wiki/L5_Society. Keith Henson and K. Eric Drexler presented a paper titled something like "Vapor Phase Deposition in the Construction of Large Space Structures". The idea was to inflate a large Kevlar cylindrical balloon at one of the Lagrange points between the Earth and the Moon. Then send lunar soil launched by a magnetic rail "mass driver" and caught in a Kevlar bag one mile across. The aluminum in the lunar soil, using solar energy, would be melted it and sprayed it on the balloon to build a large beer can essentially. Then more lunar soil would be put inside to terraform the inside like your picture.The picture above seems to be a smaller version of that. Anyway, thanks for bringing back memories and making me realize that that Vapor Phase Deposition was a form of 3D printing.