Ernst Sigmund
Sio could never have come into existence without the contribution of Mr. Ernst Sigmund. In 1933, Sigmund had fled to the Netherlands with his family from the Nazis. He started a toy store, ERSI (Ernst Sigmund), which was located at Roomolenstraat 16-18 in Amsterdam.
In Germany, he had been a toy purchaser for the department store Landauer in Worms. He had contacts with toy factories in Germany and Czechoslovakia. Among them was Schowanek, which produced wooden beads and blocks with bright colours.

Thanks to his contacts, Mr. Sigmund had expertise not only in the buying and selling of toys but also in the production process and colouring of toys. He obtained the large drums needed for colouring wooden parts with the new aniline dyes that were revolutionary for that time in a factory in Sauerland, Germany. Sio further developed this colouring technique, which became known as Siolieten.

Mr. Mertens said: "He sourced his toys from Czechoslovakia, but when it was annexed by the Germans, he looked for an industry in our country that could make toys for him. In consultation with the municipality and the ETIO, we then established this company."

The importance of Mr. Sigmund's contribution to the establishment of Sio is mentioned in an article from HP De Tijd dated February 10, 1979. It states: In order to supply his trading company, he inquires with the government whether there is any possibility to establish a small factory in the Netherlands. Assisted by the Economic Technological Institute Overijssel (ETIO), he finds that opportunity in an area where many unemployed peat workers live: the region north of Almelo. He also finds four financial backers, two of whom, Uilenreef and Mertens, take on the management of the company.

Jantje van Alles
From the establishment of Sio until the early 1950s, designs by the Sigmund couple were produced by Sio. Several horse and carriage combinations featured 'Jantje van Alles' (Jack of Everything) on the driver's seat. The painting (fine painting) of Jantje couldn't be done at the factory. It was done by a painter at home, where the Sigmund family lived. The painter continued to paint Jantjes until the 1950s and regularly delivered them to the factory in Vroomshoop.

History of the factory
Rokus was familiar with the history of Sio and was well aware of Sigmund's contribution to Sio's collection as it existed before he and Corry started working for Sio. The Groentekar (Greengrocer's cart) and Jante van Alles (Jack-of-all-trades) were purchased by him and Corry at a toy antique fair.

Departure of Directors
In the late 1970s, directors Mertens, Bronckhorst, and Uilenreef bid farewell to the factory. On the occasion of their departure and as a tribute to the Sigmund couple, a small number of new Jantje van Alles wagons were produced. Rokus and Corry also received one of these wagons.