Redditor TheHerferd carved this brain out of the rind of a watermelon using a potato peeler and a paring knife. The project took less than an hour and looks great.
We've posted about this before: here's a tutorial on making a similar brain, from 2008.
My other watermelon carving. [reddit.com]
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.