A clay project that uses no energy
Traditionally, clay is baked, or fired, at about 1000 °C over a good number of hours in a kiln - and that's only the first stage. At-home baking methods need an oven temperature of about 375°C, although for much less time. All this is much too costly. Your no-bake clay project uses clay that dries naturally over 48 - 72 hours when exposed to air.