Flat polystyrene sheets or polystyrene food box (Knighton LD7)

Does anyone have either flat polystyrene sheets (the kind that come in the bottom of boxes as shock absorption) or failing that, one of those polystyrene insulating boxes that food gets posted in? I need some for a Christmas craft I'm trying to make and just discovered the ones in our garage have been thrown out by accident! Any thickness between 1cm and 2 inches thick would work.