Gather a sheet of paper or cardstock
Place the paper flat on a surface
Fold the paper in half lengthwise
Unfold it
Fold the paper in half widthwise
Unfold it
Fold each corner toward the center crease
Fold the top and bottom edges toward the center
Fold the left and right edges toward the center
Lift the side flaps to form the box walls
Tuck the corners and edges to secure the shape
Press all folds firmly
Repeat with a second sheet if making a lid
Make the lid slightly larger than the base if needed