Gather cardboard sheets, a ruler, a pencil, a cutting tool, a straightedge, and adhesive
Measure the desired box dimensions
Mark the base, sides, and flaps on the cardboard
Cut out the cardboard pattern
Score the fold lines
Fold along the scored lines
Apply adhesive to the flaps or edges
Join the sides to form the box shape
Press and hold until secure
Reinforce the corners if needed
Let the box dry completely
Trim any uneven edges if necessary