1. Cut a doorway six inches by six inches in one of the long sides of the storage bin towards the corner. To prevent flooding, cut the opening so that the bottom of the doorway is several inches above the ground.
2. Line the floor of the bin with a piece of Styrofoam, using box cutter to cut out the piece.
3. In similar fashion, line each of the four interior walls of the bin with a piece of the Styrofoam. Perfect cuts are not necessary. Don't make the Styrofoam go all the way up to the top of the bin but leave a uniform gap of at least three inches between the top of these Styrofoam "wall pieces" and the upper lip of the bin. There needs to be room for an interior Styrofoam "roof" to fit.
4. Cut out a doorway in the Styrofoam where it is lined up with the doorway that has been cut out already in the storage bin. Trace the outline of the doorway on the Styrofoam first before cutting.
5. Stuff the bottom of the bin with straw or other insulating material to hold the Styrofoam interior wall pieces in place.
6. Cut out a Styrofoam "roof" to rest on top of the Styrofoam interior wall pieces
7. Cover the bin with its lid.