aluminium
Heinz Mack is a German artist. Together with Otto Piene he founded the ZERO movement in 1957. He exhibited works at documenta in 1964 and 1977 and he represented Germany at the 1970 Venice Biennale. He is best known for his contributions to op art, light art and kinetic art.
Hans Thoma was a German painter.
In spite of his studies under various masters, his art has little in common with modern ideas, and is formed partly by his early impressions of the simple idyllic life of his native district, partly by his sympathy with the early German masters, particularly with Albrecht Altdorfer and Lucas Cranach the Elder. In his love of the details of nature, in his precise drawing of outline, and in his predilection for local coloring, he has distinct affinities with the Pre-Raphaelites.
Carlos Cruz-Diez was a Venezuelan artist said by some scholars to have been "one of the greatest artistic innovators of the 20th century."
