STEP ONE: Paint liquid latex on your face and stick bread crumbs to itLink (Thanks, Max!)
It's a good idea to have a plate or a pie tin below you to catch spare crumbs that will fall of your face.
STEP TWO: Add more latex and breadcrumbs
At this point, you can really build up the facial features with the latex and bread crumbs. Be careful around the eyebrows and hairline, as liquid latex can tug quite a bit when it comes off. Let each layer dry before you add a new one. If you don't want a texture that is quite so thick, Dick Smith suggests using cracker meal.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.