Many have had their suspicions, but now Karl Fredrik Mattsson himself says that he is also behind the Trump coin.
- It is an ongoing paranoia that you have from day one and now I have had it for four years.
So now I think it's time to "wrap up" the project and tell about it, says Karl Fredrik Mattsson.
Artist or counterfeiter?
In 2012, he was noticed in Sweden for what looked like an ordinary crown, but as instead of the text "Carl XVI Gustav" it said "Our adulterer to king".
Then the coin sparked a discussion about whether it could be called art or whether it was a forgery crime.
Mattsson was reported to the police, but the preliminary investigation was dropped.
- When you mix an interesting text or image with a currency, something happens.
It will be dynamite, says Karl Fredrik Mattsson.
When the candidates for the US election 2016 were presented, Karl Fredrik decided to make another coin.
A 25-cent coin with Donald Trump's face on it and the text "Take a dump on Trump" - poop on Trump.
Everyday, Mattsson is a copywriter, and he likes that the rhyme feels childish and playful.
- And he has such a characteristic profile, which does great on a coin, he says.
Secret agents
But redoing the project in the US was more cumbersome and costly, he says.
Funded by an anonymous patron, Karl Fredrik Mattsson traveled to the United States where he created a list of people he could entrust his secret to.
He calls them "art agents" - those who would complete the art project.
The mission was to receive one of his Trump coins, contact the media and pretend they had received a strange coin in exchange.
Unlike his Swedish coin project, its American counterpart had no major media impact, apart from a few local media that grabbed the "news".
See the secret art agent Caio and Karl Fredrik Mattsson's coins in the clip.