This mask was used in Czechoslovak Republic during Spanish flu (1918 - 1920). This model is for women. Men would need ~10% bigger. Cross makes alignment to 0° and 45° easier.
Model created according to the following schema:
https://www.caramilla.cz/wp-content/uploads/2020/03/Prvorepublikova-rouska.pdf
The author hasn't provided the model origin yet.