Police in the Swedish city Malmö have reported that criminals in the city are using 3D printers to make working guns.

The problem for the city’s authorities is that under Swedish law it is not a crime to construct or hold a 3D printed gun’s impotent individual parts.

It is only when they are assembled into a working firearm are they in violation of the Arms Act, which is a situation Malmö’s police chief, Stefan Sintéus, is uncomfortable with.

“It is obvious that the aim is to put the pieces together into a weapon. The only thing missing is a gun barrel and a bolt, so I call for a discussion of the limits on when it counts as a crime,” said Sintéus in an interview with Swedish news programme, Skane.

Image courtesy of Malmö police

The guns were seized in January and February of this year and were later tested, and proved to be working, at the National Forensic Centre.

Police reported finding one of the 3D printed guns during a city-wide criminal sweep, while the other firearm was discovered in a Malmö parking garage.

Both guns are reported to have been constructed in the same way: by disassembling a traditionally made gun, scanning the parts, and re-constructing them via a 3D printer, which are then assembled into a finished weapon.

According to Sintéus engineers performed test firings of the weapons on six different occasions, and can confirm they are indeed in working order. The firearms therefore now qualify as illegal weapons.

Image courtesy of Kamenev

Sintéus’ comments make it pretty obvious that the Malmö police department believe 3D printed guns ought to be restricted in the same way ordinary guns are.

He also noted that while these incidents occurred in Malmö, 3D printed guns are increasingly being used by savvy criminals and the trend was “more common in Europe”.

Like it or not, we are reaching a stage where we will have to legislate for 3D printed guns, as well as their constituent parts.

“It’s not possible to criminalize a 3D printer, but it is nevertheless true that we now have people in the criminal environment that have this kind of weapon,” said Sintéus.

Researchers at Washington State University have developed a new 3D printing method that for the first time allows materials to be precisely and quickly created between the nanoscale and macroscale. As a result, it can produce materials with a strong structural resemblance to wood or bone.

The research involved the 3D printing of foglike microdroplets that contain nanoparticles of silver. The droplets are deposited at specific locations and as the liquid in the droplet evaporates, the nanoparticles remain to create incredibly delicate looking structures. Despite their apparent delicacy however, the structures are porous, have an extremely large surface area and are very strong.

“This is a groundbreaking advance in the 3D architecturing of materials at nano- to macroscales with applications in batteries, lightweight ultrastrong materials, catalytic converters, supercapacitors and biological scaffolds,” said Rahul Panat, associate professor in the School of Mechanical and Materials Engineering, who led the research.

“This technique can fill a lot of critical gaps for the realization of these technologies.”

Silver was used for the initial research due to its easy workability. However, Panat says that any other material that can crushed into nanoparticles, a description that applies to nearly all materials, could be used in place of silver.

The manufacturing method itself bears resemblance to a natural, although rare, process found over the western African deserts. In these deserts, crystalline flower-like structures known as “desert roses” form when tiny fog droplets containing sulphur evaporate over the heat of the desert earth.

Mirroring this phenomenon, the researchers’ method produced a variety of structures, including microscaffolds that contain solid truss members like a bridge, electronic connections that resemble accordion bellows, doughnut-shaped pillars or spirals. Thanks to the basis in 3D printing, they were able to do so highly efficiently, allowing for the possibility of scaling up to large-scale manufacturing.

Image courtesy of Washington State University

Going forward, the research team believes that their method can be used in a number of industrial applications. Due to the minimal waste produced and the speed of manufacture, the development of such nanoscale and porous metal structures is applicable to, for example, the development finely detailed, porous anodes and cathodes for batteries, rather than the solid structures that are now used.

If successful on this front, the researcher’s work would transform the way in which the industry operates. The shift from solid structure to porous anodes could drastically increase battery speed and capacity and, furthermore, allow the energy industry to make use of new and higher energy materials.

Panat was assisted in the project by graduate students Mohammad Sadeq Saleh and Chunshan Hu. The research is in keeping with WSU’s Grand Challenges initiative stimulating research to address some of society’s most complex issues. The team’s work is reported on in the Science Advances journal and they have filed for a patent on the method.