This video from Origami in 30 Seconds demonstrates how to make a paper box in 30 seconds. Start with a square piece of paper and fold it diagonally to make triangles from both corners. Unfold it, and fold each corner into the middle. Unfold two of the sides and fold the edges of the other sides toward the middle. Turn it over and fold the triangular corners back so they touch in the middle. Fold the corners over backwards. Take the two sides and pull them out, and fold the outside corners in to hold the box in place. Crease the insides to hold the box shape. This video is easy to follow and shows you step-by-step how to make a paper box.