Start with a square sheet of paper
Fold the paper in half horizontally, then unfold
Fold the paper in half vertically, then unfold
Fold each corner into the center crease intersection
Fold the top and bottom edges into the center line
Unfold those two folds
Fold the left and right edges into the center line
Unfold those two folds
Fold the top and bottom edges again into the nearest crease lines
Fold the left and right edges again into the nearest crease lines
Lift the side panels upward
Fold the corner flaps inward to form the box walls
Tuck the remaining flaps inside to lock the shape
Press all edges firmly to shape the box
Repeat the process with a slightly larger square to make a matching lid