 He also founded the factory "Strojne Tovarne" in Livarne Šiška and a brickworks in Koseze (which had the first circular furnace).In 1871 he joined company with F. Dobner, formerly directors of the ironworks at Dvor at Žužemberk, and in addition to building locksmithing, he also established an iron foundry and machine workshop; In 1880 Dobner exited the company, and Tönnies remained the sole owner of the "Gustav Tönnies machine shop and iron foundry".In particular, he made machinery for the wood industry and crafts, vacuum cleaners, turbines and steam engines.