Thanks. I've got some more pictures of the train itself here.
https://www.dakkadakka.com/dakkaforum/posts/list/805436.page
I wasn't really content with what I was coming up with as far as using the polar express train cars. But now I've got some much nicer train cars. (Lionel, which is probably the closest in scale for warhammer that you can get).
We'll see what happens with the re-design but I'm not in a rush. I may keep the new train "humie" for a while yet.
I was however very happy with how this factory came out. Its just a shoe box with extra cardboard glued on to represent sheet metal. The smokestacks in the back were taken from pieces of a windchime set that broke.