Each piece by Pretti.Cool is individually hand-cast from custom made rubber molds. Colors are mixed into the concrete and result in each piece being unique. They use recycled materials and can create a finished product that is 30% lighter than traditional concrete. Although a food-safe sealer is used, Pretti.Cool does not recommend putting their products in direct contact with food. Natural voids occur during casting, and some pieces will have very small pinholes.