Take a couple of handfuls of marshmallows and put them in a microwave safe bowl. Add a couple of drops of water and toss the marshmallows in it until they are all a bit damp. If you are going to just make one colour then put the whole bag of marshmallows in the bowl and add a couple of teaspoons of water. If you’re going to put flavouring oil in, add it now and add less water