I always use a kilt roll that I got through Scotweb when I'm transporting the kilt, and it's served me well. You place the kilt on a somewhat stiff plastic sheet and roll it within this. The roll is then secured by two elastics on either end and placed in a bag with handle and detachable shoulder strap. Great as a carry on when flying! Oh, and the bag is also fairly water proof, so no big worries there.