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 Gov't 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 DYI'ers to publish such things freely.
The article cites 'promises' made by DoJ to move the regulations to another department.