Ta-da! A Ravenclaw minifig! And she looks just like me, too!
"But Betty," you say, "Lego has never produced a Ravenclaw minifigure*. How is this possible?"
I will tell you: it is possible with an extra old-style Gryffindor torso, some extra body parts from Lego Pick a Brick, a Harry Potter sticker book, a pair of scissors, an Exacto knife, a cutting mat, and lots of time and patience. But hey, I think the end result is worth it (and I wasn't going to use that sticker of Cho anyway).
*Lego has produced a Ravenclaw microfigure, but that's not nearly as good looking as my personalized minifig, don't you think?