Making 80% lower receivers for AR15's has been around for at least 15-20 years.
Making your own firearms has been around since they were invented. I can go to home depot and buy some 3/4" black pipe and make a slam fire shotgun in about 15 minutes.
They used to be called Zip Guns, now they are Ghost Guns.
"If your plan is for one year, plant rice.
If your plan is for ten years, plant trees.
If your plan is for one hundred years, educate children."