Two different posts from The Firearms Blog aptly illustrate why a total ban on firearms, aside from being immoral and impractical, would also do nothing to stop people from having guns.
The second thing, and almost more impressive in my opinion is the youtube video embedded below. Some kid built a functioning sniper rifle entirely out of Lego bricks.
The rifle uses a rubber band and pulley system to propel a small Lego brick after cycling the bolt by hand. This is actually very impressive, because I mean it’s a friggin’ Lego gun!
But what this really says to me is that this is why you will never eliminate guns from the world. As long as people have machine shops, metal, and their ingenuity then you will never be able to completely eliminate firearms – some people are smart enough and skilled enough to make them.