This is the fondant I use for my cakes, mixed with white modelling chocolate (see among recipes). The best rate depends on how soft a paste you need to work with.
approx. 700g powdered sugar
1 tablespoon gelatine
6 tablespoons water
1 tablespoon butter (and some more for kneading)
2 tablespoons honey
Put the powdered sugar into a bowl.
Mix the gelatine with the water, and heat it over steam, until it melts. Then add the honey and the butter, melt it again. Now pour it into the sugar, and knead it until yuo get a homogene mass. Wrap it into plastic foil and let it “rest” an overnight. Next day knead it again, with some more butter if too hard, or some more powdered sugar if too soft. Now you may knead it together with the modelling chocolate, if you want, and also colour it.