Let’s 3D print a gun, Part 3


So you got a 3D Printer, and you went online and downloaded a 3D model of a gun. You upload it to the printer and hit print and a few hours later you have a gun, right?

No, there are a few more steps.

When you get a 3D printer, even if it is assembled, it needs to be calibrated. At a minimum the print surface (the bed) needs to be leveled to the print head.

The printer needs to be set to extrude the correct amount of material at a time, and the accuracy and precision can be adjusted.

I usually use my 3D printer to make decorate objects or toys, which are not precision parts. So I didn’t worry about much about those tweaks on my Tevo Tornado. Back when I had a Tevo Tarantula I spent countless time trying to improve performance and never really got it where I wanted it.

PLA filament goes bad when exposed to humidity. I live in Florida. You might realize what the problem is. While spools of filament are vacuum sealed, once opened they have a limited useful life span.

Various brands of printer filament may use different formulas, so you will likely need different print settings for different brands of filament. Even worse, you might need different settings for different color filament.

Running the printer at different temperatures also drastically affects the print quality. Ideally, when ever you switch filaments you would print a “temperature tower” which is a single print that is done at various temperatures so you can see what temperature provided the best qualities, usually focusing on layer adhesion.

Ugh, that is a whole lotta work. Screw it, I’m gonna skip all those steps.

One more important/boring bit of how 3D Printers work:

People use 3D modeling or Computer Aided Drafting & Design software to make 3D models of parts. Popular options for mechanical design include Solidworks, SolidEdge, Alibre, Fusion360, ProE, Creo, etc.

This software is used to make a 3D model which is then usually saved/exported into the .STL format, which is most commonly used in 3D printing.

A STL file has the data of what the model is, but omit details like scale or tolerances.

Then we have “Slicer” software. In CNC machining, we tell a machine to move along the various axis and make cuts, drill holes, etc. The code to do this is called “G Code”. Simple programs can be written by hand, more complex projects may use Computer Aided Machining (CAM) software to generate the G Code necessary to machine the part.

Slicer software takes that 3D model from the STL file and slices it into thin horizontal slices, then generates G Code to tell the 3D printer what movements it needs to make to print out that part.

When I ran a FADAL CNC Mill, our programs often had a few hundred lines of G Code. When I run my 3D printer, a print might require a few hundred thousand lines of G Code. No one would be writing a program like that by hand.

A render of the 3D printable “Liberator” pistol design.

I had initially planned to print a single shot .22 that would be mostly plastic. Figured it might survive a round or two.


BUT, and a bit one at that, there is this law on the books about “untraceable firearms”.

The United States Undetectable Firearms Act of 1988 (18 U.S.C. § 922(p)) makes it illegal to manufacture, import, sell, ship, deliver, possess, transfer, or receive any firearm that is not as detectable by walk-through metal detection as a security exemplar containing 3.7 oz (105 g) of steel, or any firearm with major components that do not generate an accurate image before standard airport imaging technology.[1]


This law, like most of our stupid laws, came about because of stupid reasons. Idiots out there thought that these new and ultra evil Glock pistols could slip right though metal detectors.

Thus, while we COULD print an almost entirely plastic pistol, it would be illegal.

I’ve learned that some people have modified the “Liberator” design to accept a steel block epoxied (permanently) into the frame.

When I started this project I intended to print the “Gluty V0.2A” 9mm pistol. It is similar to a 9mm AR15, but uses a heavily reinforced printer upper and a Glock barrel.

The “Shuty” was the first 3D printed firearm I found interesting.

Picture of the Shuty pistol, found online.

The Shuty was designed somewhat like a 9mm AR15, but used a 3d printed mag and a Glock barrel. The Gluty was an upgraded Shuty that used Glock magazines.

There is a newer version of the design called the “FCG-9” which is designed to use as many 3D printed parts as possible so that people who do not have firearm parts available to them could build it. It still uses an AR15 fire control group, but it no longer uses a Glock barrel.

FCG-9 Picture from the internet.

I hadn’t used my 3D printer in some months. The better part of a year it just sat around getting dusty. I had a new sealed package of cheap PLA+ filament. So I decided I would throw that in the printer, dust off the print bed (I use an Ikea mirror for a smooth flat surface), and start printing.

Smart thing would have been to calibrate and tweak the printer for the filament. But what fun would that have been.

The Gluty lower took about 27 hours to print, if I recall correctly. As I said in a previous post, 3D printing can not print a cantilevered structure. If you would to try and print a T shaped object, the top of the T would collapse during the print and it would fail. So you would either print the T shaped object upside down, or use supporting material to provide a scaffolding to the part.

There are many different ways to set up the support material. As I have previously done very little printing with support material, I used the default settings. This was probably a mistake.

Hours and hours later of using a scraper, plyers, side cutters, I was left with lots of support material still in the lower.

While working on the lower, I went ahead and printed the upper.

It came off the printer looking like this:

I spent many more hours removing support material.

Finally, it was starting to look like something that might actually work.

So I went and read the instructions on how to make the Gluty pistol.

Turns out it requires a little more metalworking than I am set up to do in my little hovel of a home.

I could have continued with the Gluty project, but I was starting to run low on filament, and the monitor on my laptop (Surface Pro 2017), which I use to run my 3D printer, started to fail. I decided it was time to shelve this project and go in a different route.

I looked at a variety of AR15 lower designs that are printable. Picked one that seemed decent to me and printed it out. Since then, I have assembled it, and am about to take it to the range for test firing. We will go over that next time. I’ll also go into more detail about the Gluty design.


    • Sure. There are all sorts of dry storage solutions for people who have money.

      Some people take large tupperware or similar containers, put desiccant in it and punch a small hole to run the filament out of. While I store unused filament in sealed containers with desiccant, it still goes bad.
      I have a dehumidifier in the room I have the 3D Printer. It pulls about 3 gallons of water out of the room a day when I run it.

  1. I had another thought but admit have never dealt with the humidity of Fl. but could a decent sized dehumidifier be set up that could protect the product until re-sealed?

    My old home the cellar was a humid mess during the summer till I did this and had a hose running from dehumidifier to sump pump,made a huge difference.


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