When the first 3D printed gun was fired in 2013, the blueprints were posted online for anyone to access. They were immediately taken down by order of the US government, but not before they had been downloaded nearly 100,000 times.
On August 1, plans for printable guns were allowed to be posted online once again. But attorneys-general in eight states, plus the District of Columbia, filed suits in an attempt to ban them. The court battle continues.
Additive manufacturing, or 3D printing, is the production of an object using a digital blueprint. The latest 3D printers can fit on a desk and cost less than $1,000. So long as you can find the right design and materials, you can make previously off-limit objects in your own home.