The real barrier is the knowledge, you don't need a relatively new CNC machine like that if you're just going to make a few for yourself. And old but high quality non-CNC machines are sufficient for that, and require a somewhat different set of skills.

But that's not the scenario I'm thinking about, nor is it relevant as of now in a country which has more than doubled its gun production since Obama was elected, with > 100 million being sold in that period (obviously not all those were new).