Hi….Thats a really cool way to do something like this. Gotta try i sometime. But I think in this case, there would be a problem that it will creates piles and not stacks. So I would instead create several types of book stacks, and split the books into different objects. place them around and then use randomize trasnform to give them more variety. If you randomize location on x and y axist, and rotation on z axis, they will not intersect but just be arranged differently. And the bookshelfs could be done the same way.
