He graduated from Øregårds Gymnasium in 1934 and then studied under professor Einar Utzon-Frank at the Royal Danish Academy of Fine Arts's School of Sculpture in 1936–37 and at Académie Ranson in Paris in 1938.

As a result of his Jewish background, Koppel had to seek refuge in Sweden during World War II, residing in Stockholm in 1943–44.

He attracted considerable attention for his work as a jewelry designer for Svenskt Tenn. Back in Denmark in 1945, he obtained a contract with Georg Jensen, a collaboration that lasted for the rest of his life.

[5] His designs for the company included coffee and tea sets, flatware patterns and a number of jugs and serving dishes.

[6] Koppel's work has been featured in numerous exhibitions in Denmark and abroad and he is represented in the collections of many leading design museums internationally.