But first, those tools have to get to customers' homes. That's going to be difficult for at least one new machine with the potential to make homemade firearms, because FedEx is refusing to deliver it.

Last week FedEx told firearm-access nonprofit Defense Distributed that the company refuses to ship the group's new tool, a computer controlled (CNC) mill known as the Ghost Gunner. Defense Distributed has marketed its one-foot-cubed $1,500 machine, which allows anyone to automatically carve aluminum objects from digital designs, as an affordable, private way to make an AR-15 rifle body without a serial number. Add in off-the-shelf parts that can be ordered online, and the Ghost Gunner would allow anyone to create one of the DIY, untraceable, semi-automatic firearms sometimes known as "ghost guns."

Last week FedEx told firearm-access nonprofit Defense Distributed that the company refuses to ship the group's new tool, a computer controlled (CNC) mill known as the Ghost Gunner. Defense Distributed has marketed its one-foot-cubed $1,500 machine, which allows anyone to automatically carve aluminum objects from digital designs, as an affordable, private way to make an AR-15 rifle body without a serial number.