Status: Released for public use and public development.

Make a firearm with no parts locking together, except to a single threaded rod.  The legal definitions REQUIRE that the threaded rod be defined as the Frame/Receiver. 

This means that someone should be able to design and produce gun parts which can be sold online or in store, with no paperwork.  Then the user could buy a threaded rod from a local hardware store or online parts supplier, and assemble a gun without any paperwork.  Legally the threaded rod becomes the firearm when and if an end user threads the gun parts onto it.  

This design is a simple; if poor; example using a 22 barrel sleeve, nuts, and 3d printed parts.  The real useful concept is the use of the threaded rod as the Frame/Receiver