How cool is this Halloween cardboard box costume? To create the look, find a box that's the just about the same size as your tot, and cut windows all the way around the top using a craft knife so that she can comfortably see. Build up the rest of the police box with cut sections and lengths from other cardboard boxes, and secure using tacky glue. Paint the outside blue, and add embellishments once dry. Staple lengths of wide, black ribbon to the middle, front, and back of the box to create shoulder straps.