If this bit of information doesn't offer mixed emotions, nothing will.

For those who don't understand, this technology really exists. It is getting more and more common.

The type of 3D printer I have seen in action produces a solid block of plastic, layer by layer. It works like an ink jet printer. Two "inks" are used. One ink is soluble in a solvent, the other isn't. When you are done printing the block, paper-thin layer by paper-thin layer, embedded in a block of soluble plastic is a complete device in a more substantial plastic.

You put the solid block in a solvent and what is left is a complete working "assembly" of parts, which don't have to be assembled. The complexity can be greater than a normally manufactured design, or simpler, depending on your perspective. The point is it comes out ready to use.

Printed gun -- credit HaveBlue.org

They can't make the ammo, you can't print explosives, it doesn't work that way, but while most printing is plastics, they do even have 3D metal printing.

God save us when a printer and ammo is all you need to be a terrorist - or an assassin. That day, it seems, is tomorrow...or maybe today.

At-home 3D printing is on the rise, and what was once just a lofty promise is now a reality. More and more hobbyists are acquiring affordable printers, such as the Makerbot Replicator 2 and the RapMan Universal 3D (single/dual head) printer, to manufacture just about everything from toys to working clocks.

Some hobbyists have used these printers for fast-prototyping items that are controversial -- or even deadly. It comes as no surprise that some would attempt to replicate weapons systems (or at least parts of them) in an effort to create a fully functional gun. It's not exactly clear who was the first to fabricate a firearm using a 3D printer, but one example that has garnered global attention is "Have Blue," who designed an AR-15 lower receiver (converted to fire .22 ammunition), using a CAD file in the SolidWorks file format that is openly available from CNC Gunsmithing.

After a few modifications to the original file, he set to work fabricating the receiver using around $30 of ABS filament fed through his Stratasys printer. After prototyping a small-scale model, he fabricated the full-size receiver and used it to fire 200 rounds without catastrophic failure. The proof of concept of manufacturing a 3D-printed weapon was a complete success. Now the door is open for others to try their hand at the home weapons manufacturing business.

A group of hobbyists (most of them college students) have banded together to form a company known as Defense Distributed to expand on the 3D-printed weapons systems and provide open-source software to anyone who wants it. Defense Distributed began its quest with the Wiki Weapon Project, which aims to provide all the necessary CAD software for manufacturing plastic firearms using any 3D printer. The group expanded on Have Blue's AR-15 to prove the concept of building weapons with a printer. However, instead of testing Have Blue's .22 conversion build, the group went ahead with an AR-15 conversion in 5.7x28FN, which has more firepower than a .22 but provides less pressure than the standard .223 round.

The group printed the lower receiver using Objet ABS-like filament piped through a Connex 3D printer. The printed rifle fired six shots before breaking. Apparently, the receiver's threads couldn't handle the pressure and snapped at the buffer-tube connection. The group is now looking for funding and a federal firearms license to get its project off the ground.

The problems with 3D-printed firearms aren't limited to catastrophic failure. (It takes only one bullet to kill.) There is also the issue of legality. No federal laws address manufacturing weapons with 3D printers, so anyone owning a printer could make a weapon -- even if they're not allowed to own one. The ATF considers the rifle's lower receiver as the firearm; anyone can purchase the upper receiver, barrel, etc.

The 1988 Undetectable Firearms Act prohibits the manufacturing or possession of guns that can't be picked up by airport metal detectors. This creates a loophole for hobbyists. Firearms typically require metal parts (barrel, springs, bolt, etc.) to function, and those parts can be detected. However, some companies don't want to take any chances. Defense Distributed's first attempt at funding in September through Indiegogo ended in disaster; Indiegogo froze DD's account and sent the $20,000 it raised back to the backers. In October, Stratasys terminated the group's 3D printer lease and seized the equipment from a member's home.

Like it or not, the seed of printing weapons has been planted, and the idea is sure to gain momentum through hobbyists in the near future -- until federal laws are enacted to gain control over the issue. It's only a matter of time before a printed weapon is used in a crime. Then all hell will break loose.

bumped