Back-of-Door Organizer for small laundry closet things. Screw a piece of 3/4-in. plywood to the back of the door. Add construction adhesive for hollow-core doors. Cut the plywood 3 or 4 in. shy of the door edges to avoid conflicts with the doorknob or hinges. Now you can mount as many hooks, magnets and other storage gizmos as you like.