Air-dry baking soda clay
2 cups baking soda 1 cup cornflour 1¼ cups cold water Put the dry ingredients in a medium-sized pot and add the water, mixing together using a wooden spoon until smooth. Place over medium-low heat. As the mixture warms up it will start to bubble, then quickly start to thicken. Stir the mixture constantly as it starts to solidify and clump together. Remove the pan from the heat as soon as all liquid has disappeared and the mixture resembles the consistency of soft mashed potatoes. Scrape down the sides of the pot while the mixture is still warm and turn all the dough out onto a clean surface. As soon as the dough is cool enough to touch, knead it together into a smooth ball.