Could terrorists 3D print guns?

Back in 2013, a US group called Defense Distributed headed by the then law student Cody Wilson caused a stir when they unveiled a gun they'd made - and successfully tested - using 3D printing. Made principally from plastic, many expressed alarm that such a weapon could be used to bypass airport security scans, which would make it a useful tool for terrorists. Now the same group claim to have come up with a plan for a mass-produced machine gun made the same way. They say you could just download the instruction file and feed it to your own 3D-printer at home and actually make the weapon. Tim Minshall from the Cambridge Institute of Manufacturing joins Kat Arney to split fact from fiction and tell us how you might go about 3D printing a gun...

Tim - Well, the idea here is that 3D printing is what's called an additive manufacturing process as opposed to a subtractive one.  So, in this case, you start off with nothing and build up the object you want layer by layer.  So, in this case, what's happening is you're downloading a digital file that defines this object - in this case a gun.  You send that to a 3D printer, which literally builds it up one layer at a time until you end up with an object which can be used as a gun.

Kat - So, the big question is, of course, would it work?  You know, if it's actually worth to painstakingly print one of these things. Will it actually work?  Should we be scared and running for the hills?

Tim - So, it's a great question and a very topical one. So I think - and I have to be slightly careful here - but I suspect if ISIS want guns they can probably find other ways to get them.  So there's much more convenient ways of getting hold of a gun than 3D printing one.

Kat - Yes.  It seems like it's a very convoluted way if you want to just kill someone.

Tim - Absolutely.  So the problem here is that this 3D printer's got the Star Trek replicator image that people think it's just a plug and play thing.  But actually, there's a huge amount of craft skill required to make sure that these printers work properly and big firms like Rolls Royce and G.E. use this technology, and they're comfortable with it, because they've invested millions over a long period of time in developing this technology and now they're seeing real benefits from it.  But you can't just order a printer, open the box, plug it in and then print a reliable working gun - it's just not like that.

Kat - I know. Some of my friends have 3D printers because they're a bit nerdy and I see some of the stuff the make and I'm like "mmm - that looks nice".  So a home 3D printer wouldn't have the finesse, maybe, that is needed to make a gun?

Tim - Yes and to put some facts behind this.  So the National Ballistics Intelligence Agency, which I didn't know about before, have warned that these home printed guns are a real and serious threat.  But they're a threat to the user because most of the ones they tested blew up when they first used them.  So there's a real problem here about what could look like a gun and what actually works like a gun.  But this particular one that's been in the news, which has the lovely name of the "shooty".  It is a 3D printed semi-automatic weapon and it is made predominantly of plastic parts. But, it still needs some metal parts - barrel and firing pin - things like that, and it really bulky.  To make it strong enough, out of plastic, to withstand these enormous pressures and the heat of repeated use, it has to be pretty huge.

Kat - People won't be knocking this up in their garage anytime soon?

Tim - I don't think so.  I mean there are machines you can use to print a proper metal weapon, and this has happened, but that's not the £100/£200 plastic printer.  These big ones, they cost hundreds of thousand of pounds; require very specialist supplies of gas, atomised powders, and inert argon gas to provide the right environment, and a lot of skill to get it to work right.  So those machines do exist and you could print a gun on them but it would be fantastically expensive way of doing it.

Kat - I mean, moving back to the plastic guns.  Some people worry very much that if someone's got a plastic weapon, they could get through a metal detector or maybe get a gun onto a plane.  Is that a serious risk?

Tim - There's always a risk but so the metal detector bit.  Yes, if there's still a firing pin and a barrel, then those will be picked up.  Then you could say "well what about all the other bits," but if you go online and look at the picture of this "shooty" gun, it's huge and pretty gun like and it would be quite hard to disguise that shape.  So I think the other sensors that they use at airports would pick up this strangely, glowing, gun-like object and might be a bit surprised to see it there.

Kat - And I guess you've got to have metal bullets?

Tim - You have to have the bullets as well - yes.  That's very true.

Kat - So yes, they're not going to get through are they?  I mean this is an issue, I suppose, people will always want to raise these risks of 3D printing?  Is there a risk that we could throw the 3D printer bay out with the bathwater if we say "no, this is all too dangerous - people are going to make bad stuff?"

Tim - This is a real concern and so, I guess, it's the same with many new technologies. When it comes along there's is always, very often, a good side to it and a less good side to it and we see this very clearly with 3D printing.  They are using them now - companies like Rolls and G.E. - to make these incredible, much more powerful, efficient jet engines.  In medical care, we see perfectly customised orthotics and prosthetics being produced; there are really good uses of this to improve surgical outcomes, and many, many more good things.  But I think, in the context of what we're talking about here, this is about digital rights management.  This is actually about getting access to the knowhow, and how to make a gun, and that knowhow being available freely online.  So this is really about the ability to produce an unlicensed, unregistered and hence, untraceable weapon.  Now 3d printing is just one of the ways by which that could be done, but it's really about how do we control the design of 3D printed objects.  Not just for guns but for all other objects as well.