I actually wrote the ATF a couple years back on this very topic and asked them the following:
I own a gun holster manufacturing company and have had some inquiries into doing custom holsters for guns that I do not have models for. The customer would have to leave their handgun with me for 2-3 days, sometimes up to 2-3 weeks, for the holster to be made. I have told them that I may need a FFL to do this.
Would a FFL be required to perform this type of work? Thank you for your help.
this was the response I received:
This correspondence is in response to your inquiry emailed to the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), on February 19, 2010. In your email, you requested to know if an FFL is required to occasionally obtain a firearm from a customer to build a custom holster for their firearm and returning that same firearm to them.
Based on the information you provided, as long as you are not do not engaged in the business of manufacturing or dealing firearms, no license would be required. Without an FFL you would be restricted to acquiring firearms from non-licensees who reside within your state.
You may want to obtain an FFL, if so visit http://www.atf.gov/f...ome-an-ffl.html or contact the Federal Firearms Licensing Center at (866) 662-2750 or NLC@atf.gov
You should also insure you are complying with state laws if they are more restrictive. A listing of many state and local firearms laws can be found at ATF.gov (see ATF P 5300.5 — State Laws and Published Ordinances – Firearms [2008 – 29th Edition]). If you have questions on state laws you should contact the appropriate Attorney General’s office (see http://www.naag.org/).
We trust this correspondence has been responsive to your inquiry. Should you have any further questions, please feel free to contact your local ATF Industry Operations Office. A list of ATF Office telephone numbers can be found at http://www.atf.gov/contact/field.htm.
Regards,
Firearms Enforcement Branch, ATF jcd