I have been asked many times about the playdough that I use at Smarties, parties and other events, so if you would like to make the softest most child friendly play dough then here is the recipe. The cups I use are children's drinking beakers. This recipe will last for ages, at least a month of constant use.
Are you stuck for an easy activity on the plane, play dough is great you only need a small cup filled with play dough and some cutters, you could even use plastic cutlery although this is slightly messier.
1 Cup plain all purpose flour
1/2 Cup of salt
2 tablespoons of cream of tartar
2 tablespoons of vegetable oil
1 cup of water with food colouring added
Put all the ingredients into a large non stick saucepan, stir over a medium/low heat until the mixture is thickened. Wait until dough is cooled, mould into a ball and then put into an air tight container or plastic bag with no holes.