From 1946, she managed her own studio in Oslo where she and her employees produced brightly coloured hand-woven woolen fabrics, especially upholstery.
[1] In the 1950s and 1960s, she received a number of significant commissions for interior decoration, for example for the Stiftsgården residence and the Archbishop's Palace in Trondheim.
[1] From 1953, she began collaborating with the painter Knut Rumohr, initially producing carpets with geometrical designs.
Apart from Sigrun Berg, Knudtzon is the only designer in Norway to have used rye straw for high-quality products.
[2] Knudtzon's works can be seen in the Nordenfjeldske Kunstindustrimuseum [no], Trondheim, and in the Norwegian Museum of Science and Technology, Oslo.