I have used royal icing to make stuff like that. Its a bit of a pain. I used wilton's recipe then added enough confectioners sugar until it was a firm dough. I have also experimented with adding a one teaspoon of tylose powder it makes it a little more like gumpaste but it still tastes a lot like royal icing. I have attached some pictures of stuff i have made with the royal icing.
12/2/14 at 4:11am