Based on this product's specifications, here are some alternatives and similar models
Modeling clay block giotto Giotto Glinka kamień 1 kg — air-dry modeling compound
Summary description:
Giotto Glinka kamień 1 kg is an air-dry modeling clay block from giotto designed for sculpting and handcrafts. Supplied as a single 1 kg block, it models easily by hand and hardens on exposure to air without firing. Suitable for school projects, hobby sculpting, prototyping and decorative crafts where a neutral stone-like color and easy sanding or painting after drying are required.