keep it where they cannot reach it.
i also work with clay regularly, and my cats have had access to it, but have never expressed any interest in consuming it
ok but my cats are stupjd as f**k and eat trash and my art supplies and my room is too small for me to hide it they can open my doors and reach my cardboards shelves
seems like it would be dangerous, but if you wanted to do it, i keep mine in a sealed bag/box when i am not using it, and otherwise make sure i am near enough to it to stop anything bad from happening