Federal law lets you build a firearm at home for personal use without a license or a background check, as long as you are legally allowed to own a gun in the first place. That single permission is the starting point for homemade firearms laws, but it is not the whole picture. The National Firearms Act, the Undetectable Firearms Act, a 2025 Supreme Court ruling on parts kits, and a growing patchwork of state rules all sit on top of it, and any one of them can turn a legal build into a federal crime.
The Basic Federal Permission
Under the Gun Control Act of 1968, a person who can lawfully possess a firearm may make one at home for personal use without obtaining a Federal Firearms License. No background check is required for the act of making the gun, and no serial number is required so long as the firearm stays in your hands and is never transferred.1Bureau of Alcohol, Tobacco, Firearms and Explosives. Privately Made Firearms
One condition matters from the first cut of metal: the firearm has to be intended for personal use. Build a gun with any intent to sell it and you are manufacturing commercially, which requires an FFL.
Who Cannot Legally Build a Firearm
The permission does not reach everyone. Federal law under 18 U.S.C. § 922(g) prohibits several categories of people from possessing or making any firearm:2Bureau of Alcohol, Tobacco, Firearms and Explosives. Identify Prohibited Persons
- Anyone convicted of a crime punishable by more than one year in prison
- Fugitives from justice
- Unlawful users of controlled substances
- People adjudicated as mentally defective or committed to a mental institution
- Noncitizens unlawfully in the United States and most nonimmigrant visa holders
- People dishonorably discharged from the Armed Forces
- People who have renounced U.S. citizenship
- People subject to certain domestic violence restraining orders
- People convicted of a misdemeanor crime of domestic violence
Being under indictment for a felony also temporarily bars a person from receiving a firearm, though that restriction is narrower than the full prohibition after conviction.3Office of the Law Revision Counsel. 18 U.S. Code 922 – Unlawful Acts
When the National Firearms Act Applies
The home-build permission does not override the National Firearms Act. If what you want to build falls under the NFA, you need federal approval before you start. NFA-regulated items include short-barreled rifles (barrels under 16 inches), short-barreled shotguns (barrels under 18 inches), machine guns, suppressors, and destructive devices.4Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Make and Register NFA Firearm – ATF Form 5320.1
To make one of these legally, you file ATF Form 1, the Application to Make and Register a Firearm, and wait for approval before doing any work on the weapon.5Office of the Law Revision Counsel. 26 U.S. Code 5822 – Making The application asks for fingerprints, a photograph, a description of the firearm, and a serial number you assign yourself. Starting the build before approval is a federal crime.
As of January 1, 2026, the making tax for most NFA items dropped to $0. Machine guns and destructive devices still carry a $200 making tax, but the tax for short-barreled rifles, short-barreled shotguns, and suppressors is now zero.4Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Make and Register NFA Firearm – ATF Form 5320.1 The approval and registration requirements have not changed. Making an NFA firearm without filing carries up to ten years in prison and a $10,000 fine.
Every NFA firearm must be engraved with a serial number on the receiver, along with the maker’s name, city, state, and the caliber of the weapon. The serial number must include at least one numeric character and cannot duplicate one the maker has used before.
Fully Plastic and 3D-Printed Guns
The Undetectable Firearms Act makes it illegal to manufacture, possess, or transfer any firearm that cannot be detected by standard security screening. The gun has to be at least as detectable as a reference object made of 3.7 ounces of stainless steel shaped like a handgun, and every major component has to produce an accurate image under X-ray.3Office of the Law Revision Counsel. 18 U.S. Code 922 – Unlawful Acts
If you are working with polymer or 3D-printed components, this is the line. A firearm with no detectable metal violates federal law regardless of what your state allows.
Serial Numbers on Home-Built Guns
Federal law does not require you to engrave a serial number on a firearm you build for personal use and never transfer.1Bureau of Alcohol, Tobacco, Firearms and Explosives. Privately Made Firearms That changes the moment the gun reaches a licensed dealer. If you bring your homemade firearm to an FFL for any reason, the dealer has to mark it with a serial number within seven days or before transferring it to anyone else, whichever comes first.6Bureau of Alcohol, Tobacco, Firearms and Explosives. Summary of Final Rule 2021R-05F
Several states go further and require serial numbers on all homemade firearms, including those kept only for personal use. In those states, you apply to a state agency for a unique number and engrave it on the frame or receiver before or shortly after finishing the build. Some states also fold a background check into that process.
Parts Kits After Bondi v. VanDerStok
In March 2025, the Supreme Court decided Bondi v. VanDerStok, upholding a 2022 ATF rule that treats weapon parts kits capable of being readily assembled into a working firearm as firearms themselves. The Court held that the Gun Control Act plainly reaches some partially complete frames, receivers, and parts kits.7Supreme Court of the United States. Bondi v. VanDerStok, No. 23-852
For someone building at home, this changes what you can buy off the shelf, not what you can do with raw materials. Commercially sold parts kits designed to be readily converted into working firearms now carry serial numbers and require a background check at the point of sale, just like finished guns.6Bureau of Alcohol, Tobacco, Firearms and Explosives. Summary of Final Rule 2021R-05F Building from raw materials for personal use is still allowed.
Selling or Transferring What You Built
Building a firearm with the intent to sell it makes you a manufacturer under federal law, and manufacturing for sale without an FFL is a federal crime. The Bipartisan Safer Communities Act of 2022 tightened the standard for when someone is “engaged in the business” of dealing in firearms. The current test asks whether the person’s intent is “predominantly one of obtaining pecuniary gain,” rather than something like improving or liquidating a personal collection.8Federal Register. Definition of Engaged in the Business as a Dealer in Firearms
Even a single firearm made with the intent to sell can trigger licensing and recordkeeping requirements. The line between “I built this for myself and later decided to sell it” and “I built this to sell” is one federal prosecutors scrutinize closely.
If you do hold an FFL, every gun you make has to be serialized before sale, logged in an acquisitions and dispositions record,9ATF eRegulations. 27 CFR 478.125 – Record of Receipt and Disposition and transferred only after a NICS background check using ATF Form 4473.10Bureau of Alcohol, Tobacco, Firearms and Explosives. Firearms Transaction Record – ATF Form 4473
State Rules That Change the Answer
State and local laws often go well beyond the federal baseline. The most common restriction is a ban on possessing any unserialized firearm. In those states, building a gun at home is still legal, but you have to get a unique serial number from a state agency and engrave it on the frame or receiver. Application fees vary.
Other states ban using 3D printers to produce firearms or firearm components, or regulate “firearm precursor parts,” meaning unfinished frames and receivers. Where precursor parts are regulated, buying an unfinished frame or receiver may require going through a licensed dealer and passing a background check, just like buying a finished gun.
Something being legal federally does not mean it is legal where you live, and some cities add restrictions their state does not require. Check your specific jurisdiction before you start.
Crossing State Lines
Traveling across state lines with a homemade firearm carries risk even if the gun is legal in both your home state and your destination. A state you pass through may ban unserialized firearms outright.
The Firearm Owners Protection Act contains a safe-passage provision for transporting firearms between states where you may lawfully possess them. During transport, the firearm has to be unloaded and stored so that neither it nor any ammunition is readily accessible from the passenger compartment. In a vehicle without a separate trunk, the firearm must be in a locked container other than the glove compartment or center console.11Office of the Law Revision Counsel. 18 U.S. Code 926A – Interstate Transportation of Firearms
The statute refers to a “firearm” without distinguishing between serialized and unserialized guns, but some state courts have read the provision narrowly, and a few jurisdictions have arrested travelers despite the federal protection. An unserialized firearm moving through a state that bans them adds legal exposure that safe passage may not fully cover.
Penalties for Getting It Wrong
Manufacturing or dealing in firearms without an FFL is a willful violation of the Gun Control Act, punishable by up to five years in federal prison and a fine.12Office of the Law Revision Counsel. 18 U.S. Code 924 – Penalties If the unlicensed manufacturing involves NFA firearms, the penalties rise to up to ten years and a fine of up to $10,000.
Possessing a firearm as a prohibited person is separately punishable under 18 U.S.C. § 922(g), and penalties can be enhanced by prior criminal history. Violating the Undetectable Firearms Act carries its own criminal penalties under the same statute.
Ignorance of the law is not a defense. The overlap between the Gun Control Act, NFA registration, the Undetectable Firearms Act, and state rules means a single home-built firearm can violate several laws at once if any step goes wrong.