You can build your own suppressor in Idaho, but only after you file ATF Form 1, pass a federal background check, and receive written approval. Idaho state law does not prohibit making a suppressor at home, and yet the National Firearms Act still governs every step. Starting construction before your Form 1 comes back approved is a federal felony punishable by up to ten years in prison.
Idaho’s State Exemption Will Not Protect You
Idaho Code 18-3315A declares that firearms and accessories manufactured and kept within the state fall outside federal authority over interstate commerce.1Idaho State Legislature. Idaho Code 18-3315A – Prohibition of Federal Regulation of Certain Firearms Read plainly, the statute sounds like it frees an Idaho-made suppressor from NFA requirements. It does not.
In 2018 the Tenth Circuit upheld the federal convictions of two Kansas men who built suppressors without NFA registration in reliance on a nearly identical state statute. The court held that a state legislature cannot override the NFA and that a state exemption law is not a valid defense to federal charges.2Justia. United States v. Cox, No. 17-3034 (10th Cir. 2018) The Kansas defendants avoided prison time only because the sentencing judge credited their mistaken reliance on state law as a mitigating factor. Any Idaho build has to go through the ATF.
Who Cannot Apply
Federal law bars several categories of people from possessing any firearm, and a suppressor counts as a firearm under the NFA. You are ineligible if you have a felony conviction, are under indictment for a felony, use controlled substances unlawfully, have been adjudicated mentally defective or committed to a mental institution, are unlawfully in the United States, received a dishonorable discharge, renounced U.S. citizenship, are subject to a qualifying domestic restraining order, or have a misdemeanor domestic violence conviction.3Bureau of Alcohol, Tobacco, Firearms and Explosives. Identify Prohibited Persons You must also be at least 18 years old to make an NFA firearm on a Form 1, and you must be an Idaho resident if you plan to build and keep the suppressor here.
Filing the Form 1
ATF Form 1 is titled “Application to Make and Register a Firearm.” Federal law requires you to file it, submit fingerprints and a photograph, describe the item you plan to make, and receive written approval before construction begins.4Office of the Law Revision Counsel. 26 USC 5822 – Making
You file either as an individual or through a legal entity such as a gun trust. Individual filing is simpler, but only you can legally possess the finished suppressor. If your spouse takes it to the range alone, or a family member has unsupervised access to the safe where you store it, that person is in unlawful possession of an unregistered NFA firearm from the federal perspective. A gun trust names co-trustees who can independently possess, transport, and use the suppressor, and it defines how the item passes to beneficiaries when you die. The trade-off is that every “responsible person” in a trust must submit their own fingerprints and photograph.
The application itself asks for your full legal name and address (or the trust’s), the caliber, a model name you assign, planned overall length, and a serial number you create. You also submit a recent passport-style photograph and two FBI FD-258 fingerprint cards per responsible person.
As of January 1, 2026, the $200 federal making tax on suppressor Form 1s has been reduced to $0. The fee change came through legislation signed in mid-2025. Everything else about the process is unchanged: you still file the form, submit fingerprints, clear the background check, and wait.
How Long Approval Takes
Applications are submitted electronically through the ATF eForms portal. The waiting period begins once the ATF has both your electronic submission and your mailed fingerprint cards. As of early 2026, electronically filed Form 1 applications are averaging about 36 days to process.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times That figure covers approvals, denials, and withdrawals together. Individual timelines can run longer when the background check requires additional research.
Approval arrives by email with your stamped Form 1 attached. Print it and keep it somewhere safe. It is your permanent proof that the suppressor is legally registered.
Building and Engraving
Your approved Form 1 authorizes a suppressor matching the exact specifications you listed. Major changes to the design require contacting the ATF before you proceed.
Federal regulations require permanent markings on every suppressor you make: the serial number you assigned, your legal name (or trust name) as the maker, the city and state of manufacture, the model designation, and the caliber. The serial number must be no smaller than 1/16 inch in print size, and all markings must be engraved to a minimum depth of .003 inches.6eCFR. 27 CFR 479.102 – Identification of Firearms
Most home builders do not own equipment that meets those specifications, so professional laser engraving is common. Expect to pay roughly $20 to $125 depending on the shop and the amount of text. Keep your approved Form 1 accessible; if an ATF officer asks to inspect the suppressor and its registration, you have to produce the paperwork.
Solvent Traps Are a Trap
A “solvent trap” is marketed as a firearm cleaning accessory but, with modification, can function as a suppressor. The ATF has examined many of these products and concluded that some already meet the legal definition of a suppressor out of the box. The phrase “solvent trap” has no meaning in federal law, and calling something by that name does not change what it is.
If you buy a device the ATF considers a suppressor, you are in possession of an unregistered NFA firearm the moment it arrives, whether or not you intended to file a Form 1 later. The safer path is to design and build from raw materials after your Form 1 is approved. If you plan to use commercial components, get approval first and confirm the components themselves are not already classified as suppressor parts.
Penalties for Skipping the Process
It is a federal crime to make a suppressor without an approved application, and separately a crime to possess an unregistered NFA firearm.7Office of the Law Revision Counsel. 26 USC 5861 – Prohibited Acts Either violation carries a fine of up to $10,000, up to ten years in federal prison, or both.8Office of the Law Revision Counsel. 26 USC 5871 – Penalties
Timing matters. You cannot legally begin any part of construction until your approved Form 1 is in hand. Acquiring parts with the intent to assemble them before approval can itself be treated as constructive possession of an unregistered NFA item.
Taking It Out of Idaho
Once your suppressor is built and registered, you can use it in Idaho for target shooting and hunting under state law. If you want to take it across a state line, federal law requires you to file ATF Form 5320.20, the application to transport NFA firearms interstate.9Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or Temporarily Export Certain National Firearms Act Firearms – ATF Form 5320.20 You need approval before crossing the line, and you need to confirm the destination state allows suppressor possession. Some states prohibit them, and arriving in one of those states puts you in violation of state law no matter what your federal paperwork says.