https://www.nbcnews.com/news/us-news...chines-n821516
Apparently assembling parts (which is about as hard as a beginner lego figure) is now considered a "homemade gun". I love how ignorant the people that write these things are. They make it seem like if you buy the parts it doesn't have to be legal or have a serial number. While true with most of the parts, the lowers are registered and are treated as a firearm even without any of the other parts on it.
On a slightly different topic, I actually have a friend that works as a blacksmith/forger and he has made a rifle from scratch. It is more of the style you would have seen in the 1800s though.
edit: After reading their "Ghost guns" link it seems they are talking about ordering an unfinished receiver where they ship you all of the parts and instructions to finish it, which seems like a stupid loophole to still have open IMO.