|Fig. 1: "The Liberator" gun is pictured above. There were over 100,000 downloads of the instructions to produce this gun through 3D printing in just 3 days. (Source: Wikimedia Commons)|
As 3D printing has become more affordable, popular, and accessible in the past decade, its applications to different industries and problems have continued to expand. However, concerns about how 3D printing could play into the development of weapons of mass destruction emerged after a design for a plastic handgun called The Liberator (see Fig. 1) was downloaded over 100,000 times in just three days before being taken down.  Furthermore, SpaceX has already successfully implemented the use of 3D printers in manufacturing spacecraft and rocket components.  Though the realization of a 3D printer nuclear weapon has yet to come to fruition, initial studies point to the increasing willingness of terrorists to use WMDs and the decreasing barriers to entry to weapon production that 3D printing promises as primary concerns for further research into 3D printings implications of nuclear proliferation.
Because the use of 3D printing is either classified or undeveloped, much of the scholarly dialogue about the future of 3D printing in nuclear weapon development is speculative at this point in time. However, there is a consensus that currently a nuclear weapon cannot be entirely created through 3D printing. The maraging steel that 3D printers can presently produce is not deemed strong enough to be weapon grade. Furthermore, printing centrifuge rotors is too slow and imperfect for the high-quality precision that this part demands. While using other materials such as carbon fiber could overcome the material constraints and advancements in the process for designing critical parts of the WMDs could improve their efficacy in the future, these improvements do not currently seem imminent. 
Regardless of the current limitations in 3D printing, their legitimate potential for use in nuclear weapons creates new questions regarding their place in nuclear non-proliferation agreements. A primary concern regarding the potential for the use of 3D printing in WMDs is the increasing accessibility of the equipment. As previously mentioned, the Computer-Aided Design (CAD) software that 3D printers use makes files easily accessible, which raises concerns for sharing weapon designs like the Liberator. In addition, printer costs have been decreasing as more entrants into the market drive prices down. While prices may be going down, however, the technical abilities required to operate the machinery have not increased. Thus, scholars have argued that 3D printing may be able to substitute higher technical education that was traditionally required for weapons development. By lowering the restrictively high intellectual barriers to entry, more state and substate groups could be able to put together components of a weapon over time through low-cost trial and error with 3D printers. Furthermore, 3D printing can skirt export controls and non-proliferation treaties because current IAEA standards do not account for this new development in the WMD field. 
The dual challenge presented in this report is that 3D printing makes it easier for groups to attain access to nuclear weapon design strategies, while the regulations and international frameworks for nuclear weapons development controls are not designed to address the loopholes that this new technique creates. Proactively moving to address 3D printing in the IAEA and incorporating it into international system norms regarding nuclear non-proliferation may help reduce the risk of nuclear weapon development by rogue states and terror groups.
© Kelsey Page. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 G. Walther, "Printing Insecurity? The Security Implications of 3D-Printing of Weapons," Sci. Eng. Ethics 42, 1435 (2015).
 K. Chang, "SpaceX's Big Rocket, the Falcon Heavy, Finally Reaches the Launchpad," New York Times. 22 Jan 18.
 G. Christopher, "3D Printing: A Challenge to Nuclear Export Controls." Strategic Trade Review 1, 18 (Autumn 2015).
 M. Kroenig and T. Volpe, "3-D Printing the Bomb? The Nuclear Nonproliferation Challenge," Wash. Quart. 38, No. 3, 7 (July 2015)