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 from the Bureau of Alcohol, Tobacco, Firearms and Explosives. Idaho state law does not prohibit the build, yet the National Firearms Act does, and skipping the federal step is a felony punishable by up to ten years in federal prison. Everything below assumes you intend to do this the legal way.
Idaho’s State Exemption Will Not Protect You
Idaho Code 18-3315A declares that firearms and accessories manufactured and kept inside Idaho fall outside federal interstate commerce authority.1Idaho State Legislature. Idaho Code 18-3315A – Prohibition of Federal Regulation of Certain Firearms Read on its own, the statute sounds like it exempts an Idaho-built suppressor from the NFA. It does not.
In 2018, the Tenth Circuit Court of Appeals upheld the convictions of two Kansas men who built suppressors without NFA registration while relying on a nearly identical Kansas statute. The court held that a state legislature has no authority to override the NFA, and that reliance on a state exemption is not a valid defense to federal charges.2Justia. United States v. Cox, No. 17-3034 (10th Cir. 2018) Idaho’s statute carries the same defect. Every suppressor built in Idaho must go through the ATF Form 1 process.
What You Risk by Building Without Approval
Federal law makes it a crime to make a suppressor without the required application and approval, and a separate crime to possess an unregistered NFA firearm.3Office of the Law Revision Counsel. 26 USC 5861 – Prohibited Acts Each violation carries a fine of up to $10,000, up to ten years in federal prison, or both.4Office of the Law Revision Counsel. 26 USC 5871 – Penalties
Timing is part of the trap. You cannot legally begin any part of construction until the approved Form 1 is in your hand. Buying parts with the intent to assemble them before approval can itself be treated as constructive possession of an unregistered NFA item.
Who Can Apply
Federal law bars certain people from possessing or receiving any firearm, including NFA items. You cannot file a Form 1 if any of the following applies to you:5Bureau of Alcohol, Tobacco, Firearms and Explosives. Identify Prohibited Persons
- A felony conviction, meaning any crime punishable by more than one year of imprisonment
- Current fugitive status
- Unlawful use of or addiction to a controlled substance
- Adjudication as mentally defective or commitment to a mental institution
- Being unlawfully present in the United States
- A dishonorable military discharge
- Renunciation of U.S. citizenship
- A qualifying domestic restraining order
- A misdemeanor conviction for a crime of domestic violence
If you are currently under indictment for a felony, you cannot receive firearms or ammunition during that period. You must also be at least 18 years old to make an NFA firearm on a Form 1, and you must be a resident of the state where you intend to build and keep the suppressor.
File as an Individual or Through a Trust
You can submit the Form 1 as an individual or through a legal entity like a gun trust. Filing as an individual is simpler and usually the default for someone building a single suppressor for personal use.
A trust changes who can lawfully touch the suppressor. When you register as an individual, only you can possess it. A spouse who takes it to the range without you, or a family member with unsupervised access to the safe, is technically in unlawful possession of an unregistered NFA firearm. A trust lets you name co-trustees who can independently possess, transport, and use the suppressor. It also controls what happens at your death: named beneficiaries receive the item through a defined process rather than probate, which can otherwise lead to seizure or destruction if heirs mishandle the transfer.
The cost is paperwork. Every “responsible person” named in the trust must submit fingerprints and a photograph with the application.
What the Form 1 Requires
The application is ATF Form 1, titled “Application to Make and Register a Firearm.” Federal law requires you to file it, identify yourself with fingerprints and a photograph, describe the firearm you plan to make, and receive written approval before any construction begins.6Office of the Law Revision Counsel. 26 USC 5822 – Making
The form asks for your full legal name and address, or your trust or corporate information if you are filing as an entity. You then describe the suppressor: caliber, a model name you assign, planned overall length, and a serial number you create. Each applicant and each responsible person submits a recent passport-style photograph and two completed FBI FD-258 fingerprint cards.
As of January 1, 2026, the $200 federal making tax that previously applied to each Form 1 for a suppressor has been reduced to $0. That change came through legislation signed in mid-2025. The fee is gone; the registration process is not. You still file the Form 1, submit fingerprints, clear the background check, and wait for approval before you build.
Submitting the Application and Waiting
Form 1 applications go through the ATF eForms portal. You create an account, complete the digital application, upload your photograph and any trust documents, and identify your local Chief Law Enforcement Officer so the ATF can send that office the required notification copy. After you submit electronically, the system generates a cover letter that you print and mail to the NFA Branch along with your physical fingerprint cards.
The clock starts once the ATF has both the electronic submission and the mailed fingerprint cards. As of early 2026, electronically filed Form 1 applications are averaging about 36 days to process, a figure that covers approvals, denials, and withdrawals.7Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times Individual waits can run longer if the background check needs extra research or application volume spikes.
Approval arrives by email as a stamped Form 1. Print it and keep it somewhere secure. That document is your permanent proof of legal registration, and you cannot begin construction until you have it.
Building and Engraving the Suppressor
The approved Form 1 authorizes a suppressor that matches the specifications you listed: caliber, model name, and overall length. A major design change requires contacting the ATF before you proceed.
Federal regulations require permanent identification markings. The following information must be engraved, stamped, or cast onto the device:8eCFR. 27 CFR 479.102 – Identification of Firearms
- The serial number you assigned on your Form 1
- Your legal name or trust name as the maker
- The city and state where the suppressor was made
- The model designation from your application
- The caliber from your application
The serial number must be at least 1/16 of an inch in print size, and all markings must be engraved to a minimum depth of .003 inches.8eCFR. 27 CFR 479.102 – Identification of Firearms Most home builders use a professional laser engraving shop to meet these specifications, typically $20 to $125 depending on the shop and the amount of text.
Keep the approved Form 1 accessible. If an ATF officer asks to inspect the suppressor and its registration, you need to produce it.
Avoid the Solvent Trap Shortcut
Products marketed as “solvent traps” are sold as cleaning accessories that, with modification, can function as suppressors. The ATF has examined many of these and determined that some already meet the legal definition of a suppressor as sold. “Solvent trap” has no legal meaning in federal firearms law, and the marketing label does not change what the device is.
If a product the ATF classifies as a suppressor arrives at your door, you are in possession of an unregistered NFA item the moment it gets there, even if you planned to file a Form 1 afterward. The safer path is to get your Form 1 approved first and then build from raw materials, or confirm before buying that any commercial components are not already classified as suppressor parts.
Using It in Idaho and Taking It Out of State
Once the suppressor is built and registered, you can use it in Idaho for target shooting, hunting, and other lawful purposes. Idaho law permits the use of suppressors for hunting across a wide range of game species.
Crossing state lines is a separate step. Federal law requires you to file ATF Form 5320.20, the application to transport NFA firearms interstate, and receive approval before you cross.9Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or Temporarily Export Certain National Firearms Act Firearms – ATF Form 5320.20 Check the destination state’s law too. Not every state allows suppressor possession, and arriving in one that doesn’t puts you in violation of that state’s law regardless of your federal registration.