Imagine Free Will taken to the extreme, and now you can lose the equivoque. This is the best take on the Free Will plot. This is unique, impossible and leaves your participant and spectators with a memorable effect.
Three business cards are passed face down to a participant to mix. After deciding which card will go where, your participant's actions were predicted well ahead of time. Your participant is handed control of the business cards, they are informed beforehand that each card will go to a different location, but how did they know where?
This is self-contained, no special gimmicks required, it's impromptu and this leaves your audience with no logical explanation.
Also included: A single folded prediction is passed to your participant to hold. Your participant is shown three objects. They are told in advance that they will decide where the objects will be placed. The participant decides where these objects will be placed and they can even change their mind. Yet the magician's prediction matches perfectly. And what's more, in Joel's take on the Free Will Principle, your participant is told about the decisions they will make before the effect begins -- their choices are their own.