Full apple boxes are traditionally 8″ X 12″ X 20″, the other sizes are half, quarter and eighth of the 8″ dimension. 3/4″ exterior plywood with one finished side is the most common material. There is one internal support half way down the box at a right angle to the 20″ sides. Route out one or two hand holds on each 8″X 12″ end. Don’t center the hand hold in the 8″ dimension but locate it nearer to an edge so you can grip one full apple box with your fingers and another with your thumb. That way you can carry up to four at a time.