Hello, Paul!
This castle model looks like the one edited some decades ago by the Czech publisher Albatros. A similar one was in the youth magazine
abc.
You can have a look at the data from the homepage of the AGK (German: Society for the History of Cardmodeling)
Arbeitskreis Geschichte des Kartonmodellbaus (AGK) e.V. .
Kind regards -
Papercaptain