Loaning a Firearm through a FFL

[Operator]

I am a holster maker. I like to work on custom stuff. Many times it requires that I use the customers weapon to complete the project. I'm wondering if the law allows a loan through a FFL dealer so that potentially a customer could go to his FFL ship a firearm to my FFL and then I could pick it up (sans DROS, 10day wait etc.) for the custom holster work, and then return it the same way? (I ship to his FFL etc.)

It sounds like a hassle, and I think it is, but beyond keeping the FFL monetarily happy is there any legal problem with this?

Thank you for your help.

[GoingQuiet]

It does not.