For those in the US with a combined interest in 3D-Printers, intersections of the 1st and 2nd Amendments, and legal precedents; Cody Wilson has been fighting the US Government for half a decade.
Short version: after Wilson uploaded his 3D pistol plans to his site, over 100,000 people downloaded it - this drew the attention of the US authorities, who tried to use the International Trade in Arms Regulations (ITAR) to force a take-down.
The authorities argued that by posting the 3D printer plans for a firearm, Mr. Wilson was effectively exporting firearms, and subject to federal regulation. Eventually the Department of Justice dropped the case, paving the way for DIY'ers to publish such things freely.
The article cites 'promises' made by DoJ to move the regulations to another department.
Wired's article: A Landmark Legal Shift Opens Pandora's Box for DIY Guns (archive)
Related: The $1,200 Machine That Lets Anyone Make a Metal Gun at Home
Japanese Gun Printer Goes to Jail
Suspected 3D-Printed Gun Parts and Plastic Knuckles Seized in Australia
FedEx Refuses to Ship Defense Distributed's Ghost Gunner CNC Mill
Man Who Used CNC Mill to Manufacture AR-15 "Lowers" Sentenced to 41 Months
Ghost Gunner Software Update Allows the Milling of an M1911 Handgun
(Score: 2) by hemocyanin on Saturday July 14 2018, @05:11AM
Before I got my own printer, my local makerspace was very explicit in the prohibition on using any of their machinery for making firearms.