Anthropologie put dozens of altered books to use in this store display. check out patterns featured on the Rhymes With Magic blog here. Also, this Sutherland Library video provides simple folding instructions.
get kids to make architectural components with cut-out windows, then to paint/collage with vivid pattern & color—collaborate to construct a mega building with their contributions - illuminate with christmas lights and coloured cellophane
On the actually-built side of things, these cardboard bookcases put round into practice. The spaces created within them are somewhat challenging from a functional standpoint but visually they are very impressive. It goes back to the age old furniture question: do you design with a function in mind or let users figure out their own functionality?