Do you have playmais? Our little ones love it, we bought a massive box years ago and it lasts forever. It's great to have a material that they can manage fairly easily on their own and not get into too much trouble or mess. For anyone not familiar with it, it's basically the foam stuff you get in packaging, but it's all brightly coloured and if you wet it, it sticks together. And because it's made entirely of natural food substances, if you do have a toddler who likes to eat things, it won't do them any harm. The imagination they put into their creations is wonderful to watch. This is a caterpillar world that my two built last weekend, they must have spent a good couple of hours on it together and then were able to play with it afterwards.