A new bulletin from the U.S. Department of Homeland Security warns that lethal, undetectable 3D-printed firearms may be “impossible” to contain.

A Texas law student designed and released digital blueprints for the world’s first fully printable gun, and the files have allegedly been downloaded more than 100,000 times, despite a domestic ban on distributing the files from the U.S. State Department.

“Significant advances in three-dimensional (3D) printing capabilities, availability of free digital 3D printer files for firearms components, and difficulty regulating file sharing may present public safety risks from unqualified gun seekers who obtain or manufacture 3D printed guns,” reads a May 21 bulletin from the Joint Regional Intelligence Center obtained by Fox News. 

The threats to plastic guns are so grave that private citizens who control the distribution channels have banned them from their networks. Kim Dotcom, and one of the largest consumer-facing 3D printed manufacturers, Makerbot, have both outlawed and removed blueprints.

Still, they exist on the same peer-to-peer file sharing services that distribute pirated entertainment (and legal software), said Fox News.