Yes, we’re still in early phases with additive-manufactured firearms, but the technology is coming along, as are the users.

Washbear. This is an early version with tension bars (in red on the cylinder, retained by the cylinder's black end caps).

Washbear. This is an early version with tension bars (in red on the cylinder, retained by the cylinder’s black end caps).

Big News: Working 3DP Revolver

What you just saw was a 3D printed, legal, double-action-only revolver firing six shots of live ball ammunition. This is the culmination of a lot of effort by a lot of people, not least Yoshitomo Imura who is doing three years in an unpleasant Japanese slammer for firing blanks from his original design. Through many iterations, 3D revolver and pepperbox design has improved until it’s reached the current state of the art, which is called the PM522 Washbear.

FOSSCAD writes:

The PM522 Washbear DAO .22LR Revolver by James R. Patrick. AFTER YEARS OF TRIAL AND ERROR we have the WORLD’s FIRST 3DPRINTED DAO (Double Action Only) Revolver!!!!!!!! WOO HOOOOOOOOOOOOO! With the body of the Songbird Pistol and an Imura-esque Cylinder and trigger system, this baby hold 6 dataloving shots of 22LR made for consistent shooting with a removable cylinder for easy reload. OH YES WE CAN!!!!!!! We are refining the recipe and will be releasing CAD VERY SOON! For now we have a lovely test video proving that this baby works!!MOARGUNS!!

Washbear in its case. Cylinder is designed to be an expendable part.

Washbear in its case. Cylinder is designed to be an expendable part.

Patrick is an engineering student; his own site is purported to be here. However, access is blocked by our antivirus software: “Access has been blocked as the threat  Mal/HTMLGen-A has been found on this website.” We were able to view the text on the site by looking at the Google cache of the site.

washbear printed cylindersCylinders in particular received a lot of trial, error, and trial again. The initial cylinder design took 20 hours of printer time to produce. (Who was the wag that called this technology “rapid prototyping,” and where can we get a case of whatever he was drinking?). Another iteration (see the green cylinder in the upper left) used the 3D printed part as an outer shell and filled it with epoxy resin; this is the “fill compositing” technique developed by Belter and Dollar at Yale and published in PLOS ONE.

Design for the resin-filled cylinder.

Design for the resin-filled cylinder.

Best one so far has metal chamber liners. Here’s what Patrick says:

Here’s a summary of the different cylinders we’ve tried:

  • The original multi-part cylinder with tension rods didn’t hold up. It fired two shots and cracked on the third, which deformed the cylinder enough to jam the action. The tension rods actually sheared cleanly at the point where the bullet exits the casing.
  • So we tried making the tension rods thicker. On that version, the tension rods survived firing but the cylinder still cracked.
  • So then we tried my resin-filled ABS idea. That one fired six shots, but was too damaged to reuse.
  • So I made a version with no tension rods and I tightened up the headspace, hoping that the front and rear of the cylinder would contact the frame when fired and the frame would take the pressure. FP has printed this version in Taulman Bridge (a nylon filament) and it awaits testing. He also modified that design to accept steel chamber liners.

It was printed on a Rostock Max, a deltabot-style open-source printer that’s popular with hobbysists for its open-source nature, large print area, and reasonable cost.

Washbear frame printed on the Rostock Max.

Washbear frame printed on the Rostock Max.

Much more information at the IMGUR page, and in Patrick’s website, if he can get it de-malware’d. Anybody’s guess what government agency did it to him?

This entry was posted in GunTech, Pistols and Revolvers, Weapons Education, Weapons Technology on by Hognose.

About Hognose

Former Special Forces 11B2S, later 18B, weapons man. (Also served in intelligence and operations jobs in SF).

9 thoughts on “First Documented Successful 3D Printed Revolver (&c.)


Happiness is a home workshop built weapon.

Once you build your own, it changes everything. Its going Galt with a gun.

Holding that puppy in your loving hands, you just know it makes the Hoplophobes berserk with marxist derangement syndrome.

WoooHooo! is right.


Somewhere, in the corner of Valhalla reserved for swordsmiths and other weapons techs, James Puckle, John Browning, Senior, Samuel Colt, Dr. Richard Jordan Gatling and others are having a quiet celebration, and preparing a place at their table.for another of their ilk they’ll enjoy an eternal chat with.

Tim, ’80s Mech Guy

Meanwhile in the legal section at NERF…


Don’t forget to invite Roger Bacon, Paul Vielle, Alexander Forsyth and Nicolas Lebel, else all you’ve got is a silent party with rather inconveniently shaped polearms and paperweights.


Considering the effort to come up with a working cylinder, I’d think that a more elegant solution might be to combine multiple barrels with the cylinder, eliminating any misalignment problems through indexing. If that’s a re-invention of the pepperbox, note that most of those designs weren’t quickly reloadable, but a printed version could be equipped with a second-or third- interchangable barrel and cylinder, either reloadable or one-time-use.


Hey I’m a metals guy, old school, but I belong in the composites/digital age too. Lot to be said for both epochs of technology. I really admire what these guys are doing. Yet sometimes I think they are blinded by their tunnel vision.

If they incorporated aspects of old and new technology and materials, hybridized grass roots engineering and manufacturing, they would be far ahead in their quest.

For instance, why not utilize desk top machining, fab up an aluminum cylinder, and maybe a component or two under high stress, get past the plastic composet limitations. At least for know, till suitable materials become viable?


I don’t know what’s up with the malware warning but I’ve had a couple of people say they got the same thing. I think only some brands of antivirus software have it flagged. Google say’s I’m clean though:

It’s a Blogger blog.

I’ve got a newer version of the Washbear coming out soon that should cycle more smoothly. I’ll release it when we get it working right.

Hognose Post author

The AV throwing an alarm here is Sophos.

john jay


pretty damned interesting, to say the least. very impressive. why not whomp one up in aluminum, with a little thicker cylinder walls, and see how she works.

not much difference between this and beam me up, scotty, except i thick it will be a while before we can take a person apart digitally, and put him together again. and, i sure as hell am not gonna be the first one to volunteer for a trip. but, it is amazing what you have done.

john jay