Thanks heaps for the very positive comments! It's just plain white cardboard, (white on both sides) that can be bought in any newsagents for about $1.20 - $1.50 per sheet, it's pretty easy to cut with a exacto knife. It comes in different thicknesses too. I did see the posterboard you mentioned in Kmart here... seems to be slightly stiffer but i dont think the sheets were as quite as big as the cardboard i buy.

And yes the game plays beautifully! It's still one of my favourites of all of my games