A book Christmas tree is a creative way to decorate for the holidays using old books. To make one, you will need several old books, a sturdy base, and some string or ribbon. Start by stacking the books on top of each other in a pyramid shape, starting with the largest book on the bottom and working your way up to the smallest book at the top. Once the books are stacked, use the string or ribbon to tie them together at the center, creating a sturdy base. You can then decorate the tree with ornaments, lights, or any other festive decorations you like.