Create a home base for art making.
At my house we have the Craft Cabinet, the home of all our art supplies. Over the years the materials have changed as my sibling and I have grown up, but it's still in use today, getting raided by my sister for assignments for her college classes and by me for my art projects. The Craft Cabinet has been a source of amusement and creative self-discovery over the years for us. If we wanted to make some art, we'd just open up the cabinet and pull out some crayons, pencils, glitter glue, whatever struck our fancy. And when the art making is done, all the supplies have one place to go back to, which makes cleaning up pretty easy.