Sandberg was born in
Amersfoort in 1897 and studied art in
Amsterdam. He became a follower of the
Mazdaznan movement. As a young man he traveled, serving as an apprentice to a printer in
Herrliberg, Switzerland. In 1927, he visited
Vienna, where he studied
Otto Neurath's
Isotype system at the
Gesellschafts- und Wirtschaftsmuseum. At this time, he also visited the
Dessau Bauhaus and met
Naum Gabo, a pioneer of kinetic art. Returning to Amsterdam, Sandberg started work as a graphic designer, utilizing his printing skills and Neurath's Isotype system. In 1928, he started a long relationship with the
Stedelijk Museum, and in 1932 became a member of
VANK, the Dutch Society for Arts and Crafts. He soon joined the committee that determined the exhibitions of the museum. From 1937 to 1941, he served as the museum's curator of modern art. ==Participation in the Dutch resistance==