Greetings, Kel Tec forum!

I have come into a couple of parts kits for Kel Tec P-11s and want to build them up.

In my research, I've found that there is an internal part that counts as the "firearm" for FFL purposes.  The part in question is a sort of internal frame that drops into the grip frame and the trigger group and remainder of the pistol is built around.  However, I have been unable to find any of these frames available for sale.

Does anyone know how I might acquire these frames?  Do I need to contact Kel Tec directly to arrange a transfer to my FFL?  Something else?

Thanks in advance!