3D printable guns are here to stay, but we need to ban magnets from flights too.

It’s interesting watching new technologies emerge. Someone has a bright idea, it gets hyped a bit, then someone counter-hypes a nightmare scenario and everyone panics. Then experts queue up to say why it can’t be done, then someone does it, then more panic, then knee-jerk legislation, then eventually the technology becomes part of everyday life.

I was once dismissed by our best radio experts when I suggested making cellphone masts like the ones you see on every high building today. I recall being taught that you couldn’t possibly ever get more than 19.2kbits/s down a phone line. I got heavily marked down in an appraisal for my obvious stupidity suggesting that mobile phones could include video cameras. I am well used to being told something is impossible, but if I can see how to make it work, I don’t care, I believe it anyway. My personal mantra is ‘just occasionally, everyone else IS wrong’. I am an engineer. Some engineers might not know how to do something, but others sometimes can.

When the printable gun was suggested (not by me this time!) I accepted it as an inevitable part of the future immediately. I then listened as experts argued that it could never survive the forces. But guess what? A gun doesn’t have to survive. It just needs to work once, then you use a fresh one. The first prototypes only worked for a few bullets before breaking. The Liberator was made to work just once. Missiles are like that. They fire once, only once. So you bring a few to the battle.

The recently uploaded blueprint for the Liberator printable gun has been taken offline after 100,000 copies were downloaded, so it will be about as hard to find as embarrassing pictures of any celebrity. There will be innovations, refinements, improvements, then we will see them in use by hobbyists and criminals alike.

But there are loads of ways to skin a cat, allegedly. A gun’s job is to quickly accelerate a small mass up to a high speed in a short distance. Using explosives in a bullet held in a printable lump of plastic clearly does the job on a one-shot basis, but you still need a bullet and they don’t sell them in Tesco’s. So why do it that way?

A Gauss Rifle is a science toy that can fire a ball-bearing across your living room. You can make one in 5 minutes using nothing more than sticky tape, a ruler and some neodymium magnets. Here’s a nice example of the toy version using simple steel balls:

http://scitoys.com/scitoys/scitoys/magnets/gauss.html

The concept is very well known, though a bit harder to Google now because so many computer games have used the same name for imaginary weapons. In an easily adapted version, where the steel balls are replaced by neodymium magnets held in place in alternately attracting and repelling polarities, when the first magnet is released, it is pulled by strong magnetic force to the second one, hitting it quite fast, and conveying all that energy to the next stage magnet, which is then pushed away from the one repelling it towards the one attracting it, so accumulating lots of energy. The energy accumulates over several stages, optimally harnessing the full repulsive and attractive forces available from the strong magnets. Too many stages result in the magnets shattering, but with care, four stages with simple steel balls can be used reasonably safely as a toy.

Some sites explain that if you position the magnets accurately with the poles oriented right, you can get it to make a small hole in a wall. I imagine you could design and print a gauss rifle jig with very high precision, far better than you could do with tape and your fingers, that would hold the magnets in the right locations and polarity orientations.  Then just put your magnets in and it is ready. Neodymium magnets are easily available in various sizes at low cost and the energy of the final ball is several times as high as the first one. With the larger magnets, the magnetic forces are extremely high so the energy accumulated would also be high. A sharp plastic dart housing the last ball would make quite a dangerous device. A Gauss rifle might lack the force of a conventional gun, but it could still be quite powerful. If I was in charge of airport security, I’d already be banning magnets from flights.

I really don’t see how you could stop someone making this sort of thing, or plastic crossbows or fancy plastic jigs with stored energy in springs that can be primed in an aircraft toilet that fire things in imaginative ways. There are zillions of ways to accelerate something, some of which can be done in cascades that only generate tolerable forces at any particular point so could easily work with printable materials. The current focus on firearms misses the point. You don’t have to transfer all the energy to a projectile in one short high pressure burst, you can accumulate it in stages. Focusing security controls on explosives-based systems will leave us vulnerable.

3D printable weapons are here to stay, but for criminals and terrorists, bullets with explosives in might soon be obsolete.