Americans Have Always Built Their Own Guns

There is a habit in gun-policy writing of treating the home-built firearm as something new. A loophole discovered around 2013, made urgent by cheap 3D printers, requiring novel law to close.

The premise is wrong, and it is wrong in a way that matters. For most of American history, building a gun at home was not a loophole. It was Tuesday.

The country was armed by small shops

Colonial America had no firearms industry in any sense a modern person would recognise. There was no factory. There were gunsmiths — individual craftsmen working in individual shops, making individual guns, one at a time, largely by hand from raw stock and imported locks.

When the colonies needed arms in quantity, they did not place an order with a manufacturer, because there was no manufacturer to place it with. They went to the gunsmiths. Committees of safety contracted with local shops for muskets built to a rough pattern, and the results varied exactly as much as you would expect from dozens of independent craftsmen working to a loose specification.

The rifle that became famous as the Kentucky rifle — properly a Pennsylvania product, made by German-trained smiths in Lancaster County and its neighbours — was never a manufactured article. It was a regional tradition of individual makers, each with recognisable habits of architecture and decoration. You can still attribute surviving examples to particular shops the way you would attribute furniture.

None of this was regulated, because the concept did not exist. There was no licence to make a gun because there was no licensing of guns. A man who could work iron and wood could make a firearm, and if he was good at it, his neighbours bought them.

Industrialisation changed the economics, not the law

The nineteenth century brought interchangeable parts, the armory system, and eventually the mass-produced revolver and repeating rifle. Buying a gun became enormously cheaper than making one, and most people did the sensible thing.

But the shift was economic, not legal. Building your own remained perfectly lawful. It simply stopped being worth the trouble for anyone who was not a hobbyist, a tinkerer, or someone who wanted a thing nobody sold.

That distinction — lawful but usually not worth it — is the actual through-line of this history, and it explains most of what follows. Home building has never been suppressed in America. It has waxed and waned with how expensive and how interesting it was relative to buying.

The federal government arrives, and mostly does not care

Federal firearms law effectively begins in 1934, with the National Firearms Act, and it is worth being precise about what it did. It did not prohibit making guns. It taxed and registered a narrow category of them — short-barrelled rifles and shotguns, machineguns, suppressors, and destructive devices — and it required approval before manufacture rather than after.

That structure survives today. You can still build a short-barrelled rifle or a suppressor at home. You file a Form 1, pay the making tax, and wait for approval. The order of operations is the whole point: approval first, build second. Doing it the other way around is a felony, and it remains one of the more common ways otherwise careful people get themselves in serious trouble.

The 1968 Gun Control Act reshaped commerce — it ended the mail-order trade, created the modern licensed-dealer system, and set out who may not possess a firearm. What it conspicuously did not do was require a licence to make a firearm for your own use. That has never been federal law. A person who may lawfully possess a gun may generally build one, provided the result is legal to own and they are not making them to sell.

That last clause is the one that does real work, and it is the line most of the modern arguments actually turn on.

The kit era

By the late twentieth century the hobby had reorganised itself around parts. Surplus flooded in — military rifles sold off by the ton, imported as parts kits once import law made complete rifles awkward. Builders assembled them onto domestically-made receivers. The AR-15 platform, designed around a two-part receiver and a handful of pins, turned out to be almost accidentally perfect for home assembly, and an entire aftermarket grew around that fact.

Then came the unfinished receiver. A block of aluminium or polymer machined to perhaps eighty percent of a finished lower — enough to be recognisable, not enough, on the prevailing reading, to be a firearm. Buy it unregulated, finish it with a drill press and a jig, and you had a rifle you had made yourself.

This is the point where the legal argument sharpened, because the question stopped being philosophical. If a firearm is legally defined by its receiver, then everything depends on when an unfinished block becomes one. Eighty percent? Ninety? When the fire-control pocket is opened?

The rule, and the Court

ATF answered in 2022 with Final Rule 2021R-05F, which redefined “frame or receiver” to reach partially-complete items and kits that could be readily converted into functioning firearms. In practical terms it pulled the unfinished receiver and the boxed build kit inside the Gun Control Act: serialised at the point of sale, background check at the counter.

The rule was challenged immediately, and in 2025 the Supreme Court upheld it in Bondi v. VanDerStok. Whatever one thinks of the outcome, it settled the question the eighty-percent era had left open. Kits that are readily convertible are firearms for federal purposes.

Note carefully what the case did not settle. It addressed commercial sale of kits and unfinished receivers. It did not touch the older and more fundamental rule that an individual may make a firearm for personal use. That remains lawful under federal law, as it has been since there was federal law.

Printing is the same argument with a new machine

Which brings us to the printer, and to why the historical framing matters.

A 3D printer changes the cost and the skill floor of home manufacture. It does not change the legal question, which is the same one the eighty-percent receiver raised, and the same one the parts kit raised before that: at what point does an object become a firearm, and who is allowed to bring it to that point?

The genuinely new element is not the plastic. It is the file. A design is information, it copies at zero cost, and it crosses borders in a way a milled receiver never could — which is why the legal action has moved from the object to the data. Several states now regulate the distribution of design files, and New Jersey has gone furthest, reaching unlicensed possession of them.

That is a real departure. Every previous fight was about a thing. This one is about a file, and it raises questions about speech that the receiver debates never had to answer. Whatever happens next will be argued on that ground.

What the history actually shows

Three things worth holding onto.

Home building is not new and not a loophole. It predates the industry, the regulations, and the country. The framers did not carve out an exception for it; they lived in a world where it was simply how guns came to exist.

Federal law has never required a licence to build for yourself. It has regulated categories of weapon, commerce in weapons, and who may possess them. The personal-manufacture rule has been remarkably stable across ninety years of otherwise substantial change.

The pressure has moved to the states, and it moved fast. That stability is a federal story. At the state level the ground has shifted enormously in a few years — serialisation requirements, outright prohibitions, and now file bans. Whether building at home is lawful for you is, today, mostly a question about your own state rather than about federal law.

If you are considering it, that is the thing to check first, and it is not close. Our state-by-state guide to home manufacture is the place to start.