How to build an AR-15: Step 1: Set-up
Just about everything you need to assemble your lower receiver is in the photo. The lower parts kit (LPK) is emptied and the various pieces placed on the identification sheet that's taped to the workbench. The RifleGear Aggressor lower receiver and Magpul ACS buttstock and buffer are next to the tool bin.
The lower receiver itself is serialized and for regulatory purposes is treated like a firearm. That means it required a background check, Form 4473 and ten-day wait to buy it. I think I have about four or five stripped lower receivers lying around, including one for .308. All the rest of the parts, components and assemblies are unregulated and off the shelf.
I have a set of specialized AR-15 assembly tools, including a variety of punches.