3D-printed guns: fad or threat?

Materials World magazine
1 Sep 2018

As digital blueprints for 3D-printed guns cause controversy in the USA, Kathryn Allen looks at the danger these weapons pose. 

In late June 2018, the US Justice Department ruled that digital blueprints instructing how to 3D print a gun could go back online on 1 August following a legal case between Defense Distributed – the supplier of the files – and the US State Department. However, on 31 July US district judge Robert Lasnik issued a temporary restraining order to stop the files being released. 

The DEFCAD website – launched by Defense Distributed to host the digital files – was shut down on 1 August, but, Defense Distributed’s website claims it is fighting the ruling. At the time of writing, the case is ongoing. Gun control advocates want the ban made permanent. 

The digital files were originally made available shortly after Cody Wilson, founder of Defense Distributed, fabricated the first 3D printed gun in 2013. Wilson’s 3D-printed gun was made from acrylonitrile-butadiene-styrene (ABS) – a low-cost polymer – with a metal firing pin. Its 15 components were printed individually on an industrial grade Stratasys Dimension SST 3D printer. Claiming the files violated the International Traffic in Arms Regulation, the US government forced them to be taken down shortly after release. 

Downloadable guns 

The present public threat posed by this type of 3D-printed gun – particularly in a society such as America’s where traditional weapons are relatively easy to come by – has, however, been disputed. Expensive equipment is required to print the weapons and plastic 3D-printed guns have been known to explode in the user’s hands and fall apart after use, causing more harm to the user than to whoever is in the firing line.

Research carried out by the Digital and Material Technologies Laboratory, University of Warwick, UK, and the National Ballistics and Intelligence Service, UK, in 2014, showed that due to variability in printers, software, and materials, firing a 3D-printed gun could result in failure of the weapon and injury to the shooter. 

Dr Simon Leigh, Associate Professor in the School of Engineering, University of Warwick, UK, told Materials World, ‘You could download a design for a gun that has been successfully produced on someone else’s printer and try to produce it on your printer and get a completely different result. You could try and use the same material but even then there is variability, the ABS plastic supplied by one company might not be quite the same as the ABS plastic from another supplier and those subtle differences could mean the difference between a printed gun working as intended or it blowing up in the user’s face.’

3D printers that use metal to produce guns result in a higher quality product, but these printers are considerably more expensive. Leigh said, ‘These days, a 3D-printed metal part is near enough as good as a conventionally cast metallic part, that’s why aerospace companies are experimenting with these parts to fly on aircraft. To get to that point though requires an awful lot of investment and time spent doing research to get reliable parts, it’s not the click to print process that might be familiar to someone using desktop 3D printers.’

In March 2017, researchers at the US Army Armament Research, Development and Engineering Centre (ARDEC), USA, fired the first 3D-printed grenade from a 3D-printed grenade launcher, the Rapid Additively Manufactured Ballistics Ordnance – or RAMBO. A collaborative team from the US Army Research, Development and Engineering Command, the US Army Manufacturing Technology Programme, and America Makes, USA, developed RAMBO. 

Apart from the springs and fasteners, all components of the grenade launcher were 3D printed. A direct metal laser sintering process was used to make the aluminium barrel and receiver. A steel alloy was used to print the trigger and firing pin. 

The use of additive manufacturing (AM) allows researchers to print variations of prototypes in days and quickly alter for improvements, reducing development time and costs. Parts of RAMBO required work after printing – the aluminium receiver and barrel needed machining after being removed from the build plate, and the barrel was tumbled to polish its surface, according to Army AL&T Magazine. Following this, these components underwent a coating process – type III hard-coat anodising – that created an abrasion-resistant outer layer. In total, these parts took about 75 hours to manufacture, including post-processing. In comparison, it took 20 hours to print the components for the Liberator, not including assembly time. Modelling and simulation, as well as live remote firing were used to test RAMBO’s components. This equipment, infrastructure, and expertise are not available to your average gun enthusiast, however. 

A future threat 

The backlash to 3D-printed plastic guns focuses on their lack of traceability as they have no serial numbers, the ease with which they can be attained without background checks on those printing them, and the potential for them to evade metal detectors. 

These concerns are discussed in the 2018 report Additive Manufacturing in 2040: Powerful Enabler, Disruptive Threat, published by the RAND Corporation, a US-based research organisation. It states, ‘As it becomes easier and cheaper to print weapons, the threat of kinetic attacks – violence through lethal force – could grow significantly. Through the internet, foreign terrorists and other violent extremists will likely have ready access to printable designs of new and more dangerous weapons. 

‘Additive manufacturing will also make it easier for homegrown dissidents and lone wolves to print weapons quickly in locations where they previously would not have had access to them (e.g. schools, government buildings, airports). Even these secure sites might be vulnerable to insider threats if a would-be attacker can access an AM printer and the internet.’

However, according to Trevor Johnston, Associate Political Scientist at RAND and an author of the report, there are obstacles, including the required maths, engineering, and computer-science knowledge and access to sophisticated technology, to print firearms successfully. 

Johnston told Materials World, ‘For the time being, conventional firearms will not only be much easier to acquire, but much more lethal. But, policymakers should be vigilant and consider how this precedent could shape the future threat environment. As this technology further matures – becoming more accessible to a broader swath of the population, both domestically and internationally – new threats will emerge.’ Leigh also pointed out that security scanning technologies can now detect the presence of a concealed plastic gun.


With much stricter gun laws than the USA, the UK’s Firearms Act 1968 covers the use of 3D-printed guns. The Home Office’s Guide on Firearms Licensing Law, published in 2016, states that, ‘The manufacture, purchase, sale and possession of 3D-printed firearms, ammunition or their component parts is fully captured by the provisions in section 57(1) of the Firearms Act 1968.’

It continues, ‘The expression “firearm” in the 1968 Act means a lethal barrelled weapon of any description, or component part of such weapon, from which any shot, bullet or other missile can be discharged [...] 3D-printed weapons are potentially lethal barrelled weapons and must be viewed as such in law. The method of manufacture is not material to this consideration.’

The threat posed by 3D-printed guns remains to be seen as manufacturing advances. Leigh warned, ‘I think that as this issue develops, it is going to be worth keeping an eye on how the use of 3D printing essentially de-skills the process of making a firearm. At the moment, I would say that it still requires some 3D printing engineering knowledge and gunsmith’s knowledge to make these things, that will inevitably change over time though.’ 

The concern shown by US lawmakers and the back-and-forth of the Defense Distributed case highlight a need for stricter legislation and, if lacking, to incorporate this new type of production into existing gun laws.