A designer has released 3D-printable files for a minimal AR9-style firearm receiver meant for personal home manufacture. The design is based on the AR-UN1 and is described as unfinished, with no bill of materials or supporting documents planned.

The receiver omits last-round bolt hold-open, a safety, grips, and detents. It is intended to work with ordinary milspec parts plus a hose clamp. The pack is offered only for lawful, noncommercial personal use by people in the United States who may legally make firearms, under a Creative Commons share-alike noncommercial license, with no warranty and an explicit warning about injury risk from homemade guns.