BLUF: Distributed Defense has printed and successfully testfired a pistol they call the Liberator. Following sections are LINKS, FACTS & ALLEGATIONS, SPECULATION.
Defense Distributed home
Used Stratasys SST on ebay
FACTS & ALLEGATIONS
Cody Wilson successfully fired a .380 handgun that he built on a Stratasys Dimension 768 SST 3d printer. The handgun is ABS (the plastic used in Lego building blocks) except for a small nail used as a firing pin and a 6 ounce metal slug inserted into a pocket to meet the Undetectable Firearms Act requirements. It is a single-shot pistol and must be opened and re-loaded between shots. It is called the Liberator after the WWII single-shot pistol.
Wilson claims to have test-fired another barrel built the same way attached to an otherwise standard handgun. It lasted for 10 shots.
The printer Wilson used will run in the vicinity of $15,000 if purchased used on ebay. In speculation I’ll go into possible less expensive alternatives. The SST has an xy precision of +/- 0.2mm and a z precision of up to 0.05mm. I say “up to” as the vertical layering can be controlled. The smaller the layer the longer the printing time. It prints ABS, and can use ABS, PLA (another plastic which is biodegradable and can be dissolved in a Sodium Hydroxide solution), or SST (Soluble Support Structure, proprietary, uses hot water to dissolve) as a support system.
The SST uses support structure building as opposed to solid support. In other words it makes columns under overhanging parts to keep them in place instead of building a cube of which part is solidified while the rest acts as a packed powder base. The one remaining thing to note is that the SST can and will sustain a higher temperature chamber that is slightly below the melting temperature of the print material. This helps assembly in larger pieces as the layer to which the print is being added is close to ‘welding’ temperature instead of applying the hot material to a cold surface and risking voids.
Wilson used a final treatment process referred to as acetone polishing. The piece is exposed to warm acetone fumes for a few moments which smooths and polishes the ABS. It’s typically used to remove the ‘topographical’ lines in normal builds, but it also eliminates any fine detail of the original print. Acetone will dissolve ABS if applied directly and in sufficient quantity.
First is alternative printers. Several of the more advanced “consumer” level printers will meet most of the specs of the SST for a lot less. For example, the Cubify (3d
systems) CubeX (aka Cube 2d Gen) with two heads meets the precision standards, and will run the buyer ~$3,750. Using two heads it can print the pieces in ABS while printing the support material in PLA. 3d Systems sells an ultrasound device and sodium hydroxide solution (3.5 molar strength, which is about optimum) for another ~$1400.
The CubeX uses a heated build platform and has an enclosed chamber. The chamber’s build temperature does not get as high as the SST. This can be remedied with home modifications, but the builder should recognize they’re home modifications that can violate the warranty.
The main issue with using the CubeX is that there might not be enough material in the feedstock cartridge to build all the pieces in one build cycle. There are two solutions: to do two runs, or to do yet another home modification that allows you to use a spool of thread. This latter option is common as the spool will run ~40% the cost of Cubify’s cartridges. (CubeX cartridge is $99 for ~ 750 grams of usable material). Spools cost vicinity $50 per kg.) Yet another alternative exists if you’re willing to download plans and build or purchase (for ~$399) a kit that will convert ABS and PLA pellets to filament. The cost then runs between $5 and $6 per kg.
Note this is assuming the liberator uses more than the ~750 grams of plastic of a single CubeX cartridge
The Really Dedicated builder who is able and willing to kit assemble the majority of the system can have a working dual headed device for less than $2000, and run off (assuming 1 kg per gun) a pistol for less than $10 each.
QUALITY and accuracy. Even with acetone smoothing the barrel is not going to have the tight tolerances of a standard pistol barrel. Nor will it have lands and grooves. It is a single shot “Saturday night special”. I’d not expect it to consistently hit a mansized target beyond ranges of 10 to 20 feet.
My speculation is that one “next iteration” will be some form of multi-shot. The simplest is some form of pepperpot - multiple barrels adjacent to each other, using a system that moves the firing pin from chamber to chamber. Revolvers are next most likely, and while I doubt some form of autoloader is doable I am not going to bet against it.
This is a gun that can be printed by anyone in the world and at this time never traced. Without the slug (which is a user option as the cad file just makes the pocket for it) the only thing that’ll set off a metal detector is the nail-firing pin and the bullets. Soon after use it can be dropped in a pail of acetone (nail polish) and dissolved. All a lab is going to be able to identify is that the pistol was plastic due to the ABS residue on the projectile. It’s a guarantee that it won’t be just honest and honorable people concerned about the government who make them.
I expect a great deal of consternation and furor at multiple levels up through international over this weapon. I have no idea how it’ll pan out, and in part it will depend on how and where the first few come to light. FWIW, my letter to various congressmen will recommend to let people make these, but finally put taggants in gunpowder. It’s pretty much the only way you’re going to trace these murder/assassination weapons, and with the horse out of the barn making them illegal is going to be, well … we’ve done so well at stopping porn and piracy, haven’t we?