I buy packs of A3 white cardboard and make my own extenders. Work out how high you need the box and attach them all together to fit around the sides, or to the lid to form a tall box. Or you can make a sleeve to slide over the box and sit the top on afterwards. Just remember if you make a card sleeve to attach the bottom of the sleeve to the underside of the box so when you pick the cake up it doesn’t fall out of the sleeve!!
karen,Gwynedd
