To make this organizer I bought new, empty paint cans from Home Depot (I don't remember the exact size, but they are small...you can see that in the pics). I decoupaged the cans with scrapbook paper. I bought 2 magnetic bars (from IKEA) and attached them to the wall at the back of the art shelf. The cans stay on the magnetic bars most of the time (leaving the shelf clear for making art), but if the girls want to use the art supplies at the table or outside, they can easily take them with them.
The only problem is that the cans sometimes get too heavy and fall off the bars. That usually only happens with the container of scissors.
So, there you go, Becca! This post is for you! :)