Not just plastic parts, thats the hobby printers.
You can print anything that will flow and can be held on armatures and other sacrificial supporting structures, so ceramic or metalic paste. Pop them in an oven and you have a ceramic or sintered metal like part. You can print moulds and cast into them. Green ceramic or cast/sintered metal can be machined. Your Brough Superior crank case can be made in single parts for the unit cost of a thousand today.
The military use is e-mailing hardware. You ship a printer, sacks of granules, an oven and CNC unit up the desert and the squadies can pick if they want a bit of tank track or helicopter gearbox today. The dealers will have no excuse for not having bits.
You can also make shapes that are impossible by other means. Top hat bush inserts can be double ended as assembly and manufacture are the same process, it doesn't have to press in, it grows in place. Designs may get lighter or tougher.
Bad people will email guns, knives and bomb parts, so expect controls on where the non-hobby stuff can be done. The manufactures will be able to lock their printer files on this excuse and also to prevent copying. It may kill pattern parts.
Andy
