It's possible you might be thinking of:
* Fullmetal Alchemist: The popular anime and manga series, which has two separate adaptations - *Fullmetal Alchemist* (2003) and *Fullmetal Alchemist: Brotherhood* (2009).
* Fullmetal Alchemist: Brotherhood specifically has an anime movie titled Fullmetal Alchemist: The Sacred Star of Milos, which could be what you're referring to.
* A fan-made project: It's possible you encountered a fan-made project or a story idea with the name "Fullmetal Alchemist Illusion".
Could you please provide more context or details about what you're looking for? This would help me give you a more accurate response.