Cheers for the comments @reddfox, means a lot. To answer your questions:

1) I've made a version of this train with line colourable doors as well, so you can make them as yellow as you like, it just doesn't have the Great Northern logo.

2) For props, you can either use the Mod Tools mod by BloodyPenguin, where you can export the models and turn them into props yourself, or you can use Tree and Vehicle props by Gabrielium which automatically creates prop versions of all your vehicle assets. Obviously the 2nd option is less precise and would be heavy on RAM use, but the 1st option would require more effort in order to get what you want. I can't really be bothered to create prop versions as I don't use them myself, maybe at some point though.

I love this. SO clean. Looks great in my city. Two questions:
1. Is it possible to get a version of this with yellow doors?
2. Is it possible to get a prop version with the blue doors (and/or yellow doors if the answer is "yes" to the first question.) I'd love to have some of these parked in a metro yard.

Thanks for making these beautiful models!

ooh, is that it? Ok. I don't get it a full 100%, but enough so that if I do get around to making my own assets with custom textures, I can remember this is something to watch out for. Thanks for explaining!

@Sp3ctre18 Basically I'm doing it in a really lazy way, doing the entire texture when editing the model, then letting blender automatically UV unwrap, meaning that it treats the faces on 2 sides of the boundary as non-continuous, meaning they're separate in the diffuse texture. So the black lines that are seen are due to the background of the diffuse texture leaking in since resolution has to be decreased to make the file size not insane.

Yeah, I understand, most seemed good enough to me. Why does the UV mapping matter? I'm talking about a line you draw in the texture, right? Does it have a role when mapping?

@Sp3ctre18 Cheers for the feedback, I've been trying my best to learn as I go along, but I do agree that my assets are far from the standard that some others are able to produce. I have an idea of how to fix that but I think I'm gonna have to try and learn how to do the UV mapping properly.

Maybe it's just because this train in particular is so white, but the edge / panel Gap / joint lines seem too simple, thick, and/or dark. They make it look a bit cartoony, particularly because of the ones that seem to be on simple edges and not actual joints or anything, so those seem odd. Hope you can improve on that, but looks like a cool train. I've saved one of your previous ones for future subbing, thanks for making and sharing!