Why not iust buy guns? Or buy gun parts and make them? What is it about printing that's appealing?
I don't let anyone fire anything I own without an intro safety course and firing practice with a laser bullet, so I don't intend to throw free guns into crowds, but I do know that there is a large group of responsible people who go unarmed for the sole reason that the price of guns is very, very high.
At $500/pop, I can't afford to be charitable. At $50-100, these become birthday gifts.
The economics behind gun parts is wacky, and home production would be a radical shift in technology to finally send the cost downward.
Of course gun manufacturers would lobby against any home printing. How could they sell $2400 rifles when a decent rifle would only cost a tenth of that to build at home?