Given that it's relatively simple to craft a gun (3D printing, metalworking, etc.), how would you propose to implement the bans given that there's a relatively

Given that it's relatively simple to craft a gun (3D printing, metalworking, etc.), how would you propose to implement the bans given that there's a relatively large subset of the population hell-bent on staying armed? Honest question--I've never owned a gun and I don't intend to.