Totally legal in Indiana, you can make up to 10 - anything more requires an 07 FFL (IIRC). Perhaps I just spoke to soon, I didn't watch but a few seconds of the vid, however, I know in IN you can make your own unserialized weapon.
When I googled about this I came across a few articles about the BATF being unhappy about this, and possibly changing the definition of "firearm" to include the upper. If you're interested it might be a good idea to get the parts before the administration does whatever it plans to do.
Having said that, every site that I have looked at is out of stock. Big surprise.
If the new ban banned the manufacture of AR's and AK's etc, then this would become illegal as you must abide by all state and local laws, such as someone under the age of 18 couldn't build a rifle this way legally, as they cannot own a rifle legally under 18 unless gifted to them.