In a bowl, mix 4 c icing sugar and 1/2 c cornstarch with a pinch of cream of tartar
Bloom 1 envelop of gelatin in 1/3 c water. Let stand for 5 minutes then heat on microwave for 30 seconds, stir, then pour the liquid into dry ingredients, mix with wooden spoon
Knead mixture until smooth then wrap with plastic cling wrap and store in tupperware or similar container.
Let rest for a couple of hours or overnight
Roll, cut, color as you please and have fun :D