The principle in making a box that can keep the ice cream from melting is to prevent the heat from entering the box. Now what makes the heat from transferring is its ability to be conducted. Many things can be considered conductors like metals or glasses. However if you want to keep it from melting, you have to build a box which is completely insulated. There are coolers in the market that are working efficiently for this purpose. In making a box that can keep an ice cream from melting, you can use some materials such as polyurethane or polystyrene (Styrofoam) or any other insulation foam. First, you need a box that is tightly wrapped with tape to retain its rigidity when the insulation is installed. Next, you can add the polystyrene in the inner walls of the box. Use polyurethane glue to stick things together. Finally, use the insulation foam to make cooling last longer.