system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is it so hard for a third party replicate money perfectly so that it can't be told apart from the real thing?

I understand it is illegal but the question is, if a bank can print money, why can't a third party make a perfect replicate of a note, for example, so that there is no difference between that and a real note.
gpt
Banks don't print money, mints do. To make currency of equal quality to a mint, you need the resources of a mint. Many countries don't even have that (they outsource to other mints). Doing it yourself is nearly impossible because they use techniques that, on purpose, are way out of the league of almost everybody. 

The only real "perfect grade" counterfeits known to exist at the moment are actually suspected to be the work of a national mint.