The point above was that even in the case of making something illegal, it doesn't stop people from physically doing it.
In the USA it is legal to make your own guns.
> The Legal Framework for Individuals: Making a firearm for personal use is legal. Making a firearm for personal use without a federal manufacturing license is legal. This has always been the case, even after the enactment of the Gun Control Act of 1968 ("GCA"). http://freedomblog.skylarklaw.com/2014/10/is-making-firearm-...
Interesting that this came up in a thread about Bitcoin.