Karl Fredrik Mattsson held a press conference Wednesday to reveal himself as the creator of the coins, which labeled King Carl XVI Gustaf as "Our whorer of a king," The Local.se reported Thursday.
Mattsson said he did not put the coins in circulation, but rather distributed them to family and friends with instructions to show them to the media.
Mattsson described the project as an art "experiment."
"I won't explain why. I don't think that it's my responsibility as an amateur artist to explain art for someone," he said.
The amateur artist admitted he could face charges for the stunt, which apparently referenced allegations of infidelity against the king in a 2010 biography, "Carl XVI Gustaf -- The reluctant monarch."
"I am ready to be charged if the king wants to charge me," Mattsson said.