In case you are thinking of doing a class with playdough, below you can find a fantastic recipe. It is cheap to make, eatable and lasts months!!!!!!! I made 2 kg for a party and we are still using it (that was in Feb and now is June!).
½ cup (2oz/50g) of cooking salt
1 cup (4oz/100g) of plain flour
2 tablespoons cream of tartar
1 cup (8floz/200ml) of water
1 tablespoon of oil
Food colouring if desired
• Mix the dry ingredients in a saucepan.
• Mix the water, oil and food colouring. Add them to the dry ingredients.
• Cook on medium heat, stirring until the mixture forms a doughy consistency and begins to come away from the sides of the pan.
• Remove it from the heat and allow it to cool slightly.
• Turn it onto a floured board and knead it.
• Store in an airtight container or plastic wrap in the refrigerator.
(I did not put it into the fridge just in an airtight container and it lasts aaaaages)