[3] He represented Zenit at international exhibitions in the 1920s (Belgrade, Bucharest, and Moscow),[4] Seissel studied at the Technical Faculty in Zagreb under H. Ehrlich,[3] earning a degree in architecture in 1929.
He worked at the Department for the Regulation of Zagreb (Odsjeku za regulaciju grada Zagreba), and later became the director of the School of Applied Arts (Obrtne škole).
Following the Second World War, he worked at the Ministry of Construction (Ministarstvu građevina), and from 1965 was a professor at the Faculty of Architecture at Zagreb University.
[5] In 1937 he received the Grand Prix and the Order of the Legion of Honor from the French government for designing the Yugoslav pavilion for the World Exhibition in Paris.
As an architect, Seissel was involved in urban planning for parts of Zagreb, as well as studies for other regions such as Makarska, Baško Polje, Šibenik, Mljet and Nikšić.
[5] In addition to his career as an architect, Seissel was active in the avant-garde art movement in Zagreb from the 1920s, most notably related to Zenit magazine.
His constructivist forms have geometrical designs and interlocking planes, for which he used modern transparent materials that allowed light to become a contributing element.
His best-known series consists of 19 verbo-visual works in watercolour, ink and tempera called 3C i tričarije (a play on words that is difficult to translate).