Use about a large handful of mini marshmallows and melt for about 20-30 seconds in the microwave (depending on how hot yours is). Stir and heat until it is smooth
Immediately add your food coloring and add powdered sugar slowly mixing as you go until it is as thick and pliable as you would like. Careful, it may be quite warm so use a spoon.
Lay out a piece of parchment paper to use as a playing surface once it is ready.