Place the marshmallows in a microwave-proof bowl with the coconut oil
Heat for 30 seconds in a microwave, 10 seconds at a time. Let the marshmallows puff up, stop the heat until they collapse down and start it again.
Add a few tablespoons of cornflour and drops of food colourings into the melted marshmallows.
Stir everything together until it's thick and too hard to stir.
Take the mixture out and knead it on a clean surface sprinkled with cornflour.
If it gets too sticky add more cornflour. If you need to make it smoother add a small amount of coconut oil at a time.
When it feels like playdough and is smooth and easy to roll into a ball and out again, it's ready to play with!