Dominion (Card Game) Wiki
Type Action
Effect Copper produces an extra 1 Coin this turn.
Cost 4 Coins
Set Intrigue
Illustration Claus Stephan

Additional Rules from the Rulebook[]

This just changes how much money you get when playing Copper. The effect is cumulative; if you use Throne Room on Coppersmith, each Copper that you play that turn will produce 3 coins.

The Secret History of Coppersmith[]

In an article on Board Game Geek, Donald X. Vaccarino commented on the development of Coppersmith:

One of the times when I took something out and needed to replace it, I tried specifically to think of a new way to build up your money. This was the result. Double your Coppers! There are several directions to go with Coppersmith, but it's one of the trickier cards in the set. Those Coppersmith decks don't just build themselves.[1]