When Is Counterfeit Counterfeit?

Making or possessing the moulds themselves would be illegal, as it is illegal to make or possess items which could be used to create counterfeit coins. US Law Code, Title 18, Section 487. So even if the coins you made from them were "clearly fakes", having the dies or moulds means you could in theory try to make much more realistic-looking copies from those moulds.

Take a quarter and stamp COPY in it in san serif letters at least 2 mm high and the word being 6 mm long, then use that to make your mold. The resulting pieces when they are made will be marked in such a way as to make them legal under the Hobby Protection Act.

I do believe that you're Dutch, so then the Dutch law applies if you perform your trick in The Netherlands. Here's the article that's relevant about valsmunterij: http://www.wetboek-online.nl/wet/We...cht/209.html

For short, you can create your coins without penalty, as you clearly show that you don't intend to use your coins as legal tender. You use different materials with a different color than the original and you use them in a magic trick, not in a shop. Not that any Dutch shop accepts American quarters, but that's another story.

However, if you'd reproduce any coin with the intention to use it as legal tender and you get caught doing so, then you're facing 9 years in prison and/or a fine of up to 82.000 euro. But as this clearly isn't the case here, I suggest that you don't have to worry too much. Just make sure you don't use original dies and that your audience knows that it's not real money.