Sweet! You can bring the poster and the picture to the nearest Photography Class (most likely at a highschool) and the teacher can do it for you for a cheep price. I was in photography class and did that for me and jasper. It was pretty cool. I won best picture of the year award. My teacher said it was the best one he'd seen since he came to work here. Once there photo shopped together you could bring it to festival. I know they put pictures of people on cakes all the time. I did for my great grandpa one year. You could also try asking a professional cake decorater at any cake supply store. We have one here in WI but I'm not sure if she puts faces on cakes. I hope you figure it out! She'll be so happy!