Gather corrugated cardboard boxes from your local grocery store or supply store. The boxes should all be the same size. Otherwise, you will have to add up the sides of boxes. The sides, when added together, should be equal to or greater than the length and width of your mattress. A standard full mattress measures 53 inches by 74 inches. Each cardboard box should be in good condition, without any dents or holes. If any box is damaged, it will slump with the weight of the mattress.
Tape all the boxes shut, leaving one side open. Then, line the boxes up in four rows and three columns. When lining the boxes up, have the open end of the box face the outside of the formation. (The box in center of the formation will be surrounded on all sides. If desired, tape this box shut on all sides.) Use packing tape to link the boxes together, to prevent them from shifting.
Fill the boxes with books, collectibles or miscellaneous items. Since the box opening faces the outside, you can store and remove these items quickly and easily. The items inside the boxes will also help to anchor the bed frame and provide added support.
Measure the width and length of the cardboard box formation. Mark the dimensions on the large sheet of corrugated cardboard with a marker. Cut the cardboard using the box cutter. Lay the sheet on top of the cardboard boxes. This sheet will serve as an intermediate layer between the bed base and mattress.
Take the width and half of the length of the cardboard box formation. Mark and then cut the corrugated cardboard according to these dimensions. This will serve as the headboard of the bed.
Attach the headboard so that it stands vertically at one end of the base using a hot glue gun. Allow time for the glue to dry.
Lay the full-sized mattress over the cardboard base to finish.