Drawing back to the original point, who is building a drone, or anything. There is only one guy I know of (primitive technology on you tube), and the most advanced thing hes made is a hatchet and charcoal.

This is like saying you didn't make homemade bread if you didn't grow the wheat out back. It is a pointless statement countering an assertion no one asserted because the rest of us know that home made bread means from store bought ingredients unless specified otherwise.

Likewise, I doubt that too many people are etching flight controller PCBs and building brushless motors from scratch in their garages.

You’d be surprised then - first of all, no “hammer-forging” is required, nor is 7075 whatever.

Take this for example (warning, language!) https://www.northeastshooters.com/xen/threads/diy-shovel-ak-...

This is actually my point. It didn't say "no one" is doing it. Even though his means are very crude, he still needs a furnace, a welder, and a lot of other tooling (receiver jig, etc.) to get to the point where he can use a bucket of pre-fab parts (most notably the barrel).

That guy is building a receiver, then assembling. Most people who are into it are just assembling.