I note with interest (courtesy of a link at Old NFO's place) that the US Navy is looking at a 3D-printed, easy-to-assemble submersible vehicle.
A team of researchers from the U.S. Department of Energy and the U.S. Navy have created the military’s first 3D-printed submarine, an achievement that may have the potential to accelerate the defense R&D process.
The sub – called the Optionally Manned Technology Demonstrator – is a 30-foot submersible made of thermoplastic resin, and it closely resembles the covert infiltration mini-subs used by the Navy SEALs. The hulls for these subs currently take three to five months to build and about $600-800,000 each. But the Naval Surface Warfare Center Carderock Division's Disruptive Technology Laboratory (DTL) partnered with Oak Ridge National Laboratory (ONRL) to bring down the expense: using ORNL's Big Area Additive Manufacturing facility, they printed the hull in six sections at a cost in the tens of thousands. A contractor assembled the sections into the final product. The whole process took weeks rather than months.
There's more at the link.
If this works, think of what it'll mean for deployment. Instead of having to ferry something like this (for example, for use by Navy SEAL teams in a combat zone), a 3D printing facility can be installed aboard something like a Landing Platform Dock, or LPD. I'm sure the US Navy's San Antonio class LPD's could accommodate it. The Navy could "print-on-demand" however many of these it needed, and simply sink or otherwise discard them after use. They'd be cheap enough to be disposable. The technology need not be limited to submersibles, either. Boats, aircraft parts, even weapons housings could be produced in this way. Think of the saving in shipping, through not having to get them all the way from rear bases to the front line.
This might indeed be a revolutionary development.