Do I really want to give you a plan when the project is for a design and technology class? Hmmm.
At any rate, the term "revolving bookcase" brings lots of pictures to my mind, so I guess we need to know what you want the thing to do, exactly. Do you want something like a card stand, where all you have to do is stand in one place and spin it around on its vertical axis? Is this a space saving device where you want to be able to shelve books in multiple layers deep on the wall? How do you want it to revolve?
The shoe rack that Kurt Russel's character built in Overboard comes to mind....
Please post back with your requirements, or maybe we can generate a dialogue here. Henry, Jay J, bc and Dodgeman should have lots of ideas too!