i have used long narrow boxes, cut several square pieces of cardboard the same size as the inside of the box, then stab a hole through the middle of all of them, then push the axle through the center of the cardboard blocks to various distances from the ends, and slide axle with carboard spacers into the end of the box, and put your packing in around. the carboard blocks hold the axle in the middle of the box and doesnt allow it to move around. many ways to skin a cat.