For storing students ceramic work, start collecting boards of various sizes and keep the plastic bags that the clay comes in. I "inherited" these materials and have been using them for 13 years. Have the students place their projects on the boards, lay a damp paper towel on the project, and place the entire board and project in a plastic bag. They can then tape it or fold the bag under the board. I usually have them put a piece of tape with their name on it in a visible area on the outside of the bag so that they don't open someone else's by mistake.