3 rolls of tape , an old doona or 2 blankets and lots and lots of cardboard . Extra cardboard on the ends , make that two .Then another layer of cardboard . Keeping it as tight as you can with the tape as you go . It's the total volume that costs , not the weight .
Ps, With a fat texta write sender and receiver details . Don't just rely on the con note . I lost a board that way

Bubble wrap is your friend .l find Ecocell the best for carbon boards.