Grundig really took off at the end of the Second World War. In 1945, he opened a new radio production facility in Fürth. At the time, producing radios was subject to a licence due to strict Allied control across the country. So, Grundig came up with an ingenious idea of selling a build-your-own radio kit that Germans could use at home. The product was marketed as a ‘toy’ called Heinzelmann, and helped cement Grundig’s status as a real innovator.
Next, Grundig expanded his business under the name "Grundig Radio-Werke GmbH". As sales continue to rise, the company became a pioneer in home entertainment electronics. In 1951, Grundig marketed its first portable television set. It was one of the first companies in Europe to do so. By 1979, the company was employing more than 38,000