Take a square sheet of paper
Fold it in half horizontally and unfold
Fold it in half vertically and unfold
Fold each corner toward the center
Fold the top and bottom edges toward the center
Fold the left and right edges toward the center
Unfold the last two folds
Fold the top and bottom edges back to the center
Lift the left and right sides upward
Fold the corner flaps inward to form the box walls
Press the corners and edges firmly to shape the box
Repeat with a second sheet of paper to make a matching lid