Basically, you can use anything you want. I think some have used rice, some have used beans, our choice was egg noodles. All you need is a couple of bowls, shovel, cup, bucket, and egg noodles. This entertained him for about an hour, and he even brought all the bowls into the kitchen on his own when he was finished. Without being asked I should add <3. (ignore the dirty shirt, I am pretty sure he spilled more of his applesauce on him this morning than he actually ate.)
Here is the link.