After World War II, Dell manufactured silver goods and opened a jewellery shop in Wiesbaden in 1948, which he operated until 1955. He died in Wiesbaden in 1974.
Beginning in 1926 Dell sketched lights, at first for the New Frankfurt-project. As an early industrial designer and pioneer of plastic design, Dell used bakelite and aminoplastics as materials for his works for Molitor-Zweckleuchten in 1929-30. Well known are the lights for the lamp factory Gebr. Kaiser & Co. in Neheim Hüsten beginning in 1933-34, which were produced in large quantities.