A friend has this game and after playing it for more than 20 times we came to the conclusion that it really needs an insert. After searching around for options, we've found hex laying aids, flags and other cool projects however no organizer.
So, we used https://github.com/dppdppd/The-Boardgame-Insert-Toolkit to create a very rough, loose insert for this game to accommodate the additional flags and laying aids besides the game.
The went towards the looser fit than a tighter fit with support for other expansions in mind.
The insert was printed on a Bambu X1C in PLA with default settings for a 0.4 nozzle.
The flags and laying aids can be found here:
Dorfromantik - Flags and Task Marker Holder by pheraph | Download free STL model | Printables.com
Dorfromantik Laying Aid by FlavaSava | Download free STL model | Printables.com