Another reason can be found in the marketing of the toy. Just googling shows various pictures of billboards from the 20th century advertising for model trains. And most of these pictures show little boys, sometimes with an older man that should probably represent the father.
The advertisement shown here is from the 1920s, advertising for the model train company Märklin. You can see five children of various ages standing in front of a toy store. One boy is holding up what looks like a little booklet, while two others are reaching for it. He is holding the new Märkin catalogue. Interpreting the clothes, we see three boys and two girls, but only one of the girls is reaching for the catalogue. In the for ground are the two boys, who seem to fight over it. This advertisement does not exclude the girl, but it does put the boys as the audience first.
In the marketing world, boys are seen as active players, interested in building, investigating and exploring, while girls are more passive and interested in social behavior (Reich, Black & Foliaki, 2018, p.83ff). This has an influence on how children see themselves and build an understanding of gender and identity (Hans et al. 2019, p.250). Marketing toys towards boys can therefore limit girls play and narrow their vision and imagination (Coyne et al., 2016, p.244f).
Advertisement, behaviour and gender stereotypes seem to have a big impact on what toy fits whom. Model trains and railroads represent an active, technical toy that is stereotypically advertised towards boys and their fathers. It is no surprise that the model train world nowadays is therefore a male-domitaed world (eliott, 1995, p. 14; Stonies, 2016, p.194).