Combine all ingredients in a pot over medium heat, stir constantly with a wooden spoon. Mixture will begin to bubble and then quickly turn into a dough resembling mashed potatoes, about 4 to 5 minutes. Remove from heat and turn out onto counter. Once cool enough to handle, knead dough until it is smooth and pliable. If it is slightly sticky you can dust with a bit of cornstarch while kneading.
Roll out to ¼“ thick using a rolling pin. Add texture at this point, or begin cutting out shapes with cookie cutters. Place on a cookie sheet and allow to dry at room temperature overnight. Flip over to dry the other side a second night. If you have a food dehydrator that also works to dry faster, use on lowest temperature setting and dry for approximately 2 hours. Make sure ornaments are completely dry before painting.