Make the insulation panels to line the inside of the box. Measure every inner side of the box and write down the measurements. Measure and mark the Styrofoam insulation to make a panel for each side of the box. Use the ruler to measure each panel and draw lines to indicate where each panel should be cut. Cut each panel out along the lines with the X-Acto knife.
Place the garbage bag into the box and adjust it to line the box. Push the bag into each corner and make it smoothly lined up with the inside of the box. Cut off the excess bag that may extend out of the top of the box. Duct tape the edges of the bag to the box, if desired.
Glue the panels to the liner to secure them in place. Apply glue to one side of the bottom panel and insert it into the bottom of the box. Add each side in the same fashion, applying the glue and then inserting the panel. Place the side panels into the box in opposite order (two opposite sides first, then fit in the two remaining opposite sides). Do not add the top insulation panel yet.
Fill the cooler with ice and food items. Place the top Styrofoam panel on top of the food and ice and close the box.
