First, I divided and containerized the "drawing supplies" (think markers, colored pencils, crayons) in these clear pencil boxes (The Container Store, $2.49). The cube will fit up to 5 of these containers.
I'm really happy with the way these containers show what is in the bin and give a home to each type of item.
I also added these Like-It Magazine Files (The Container Store, 2 for $9.99) to the bins used for the coloring books, construction paper and activity books. Using the vertical structure of the magazine files makes finding things easier and prevents books and papers from being crushed at the bottom of the cube.