Richter marketed the sets under an anchor trademark and they became enormous. Forty-two thousand sets sold in 1883 alone. Over the decades more than six hundred different sets were produced and over a thousand stone shapes.

The list of children who built with them is unusual. Albert Einstein had a set, and some of his stones survive. So did the physicists Max Born and Robert Oppenheimer, the computer graphics pioneer Ivan Sutherland, and Walter Gropius, who founded the Bauhaus. Sets have been exhibited at the Louvre and the Deutsches Museum.

Production stopped in 1963 under the East German government, and the machinery was given away. The sets were revived decades later, and since 2017 they have been made again in Rudolstadt by Ankerstein GmbH, owned by a local workers' welfare association.

Materials and method