Supplies Needed; Cardboard box, blue construction paper, blue painters tape, and a print out of Post office logo (if desired).
Tape box shut at both ends. Cut a slot, in the center of the box, wide enough for letters to for through. Cover the box in blue paper, and use the painters tape to smooth over the mail slot. Glue on the post office logo, or write "Post Office" on the front of the box.