“3D printing” is a bit of a misnomer and I prefer its more technical term, additive manufacturing. That nicely illustrates how it works – you add material to build up whatever you want. It also highlights the difference between it and conventional machining, which is substractive – you remove material from a block until you’re left with the object you wanted. This is of course highly inefficient and wasteful compared to building up the object using only the materials you need.
Desktop 3D printers for home use are still limited to printing resin. This has become one of the biggest criticisms of the technology – that we can only print so many little plastic baubles. This is true of course, but as always, people get hung up on the first iterations of a new technology and dismiss it completely. Small consumer-grade printers can only make small plastic objects, but there are professional “printers” that can assemble metal objects too. It’s in that arena that things become very interesting.
Take GE for example, who will “print” parts for jet engines. That’s miles away from printing off a little plastic Super Mario sculpture – these are highly engineered parts built to extremely tight tolerances. If we can print airplane parts, we can print car parts too. We can print appliance parts. Intensive research is underway to print integrated circuit boards. See the potential?
Imagine your mechanic printing off replacement parts for your car in his shop using inexpensive buckets of metal powder and a 3D model of the part, either downloaded or scanned in from the old broken part. Or the appliance repair technician printing off a new circuit board to replace the dead one in your refrigerator. We might go back to the days when you could actually repair household electronics!
And of course the use case for the US Army is particularly compelling. Supply is an incredibly complex and expensive part of maintaining an army, and the ability to create parts on-site in the middle of nowhere offers not only tremendous cost savings but also great convenience. We can even print guns now. We could conceivably airdrop a printer and a few technicians halfway across the globe, and have them print off everything from vehicles to weapons as needed (and maybe even melt everything back down when they’re done).