There was a photo of a 4-4-0 that was also weird on a youtube video, but I lost track of it and couldn't find the video again. Thankfully, its photograph was in the Smithsonian archives. P.S. I think train design pre-civil war is weird in general, simply because the tech was still new. I own a copy of a book called "B&O Power: Steam Diesel and Electric Locomotives of the Baltimore and Ohio Railroad" and there are a few odd designs in the first few pages.
https://www.si.edu/object/archives/components/sova-nmah-ac-0163-ref548

can you make the fontaine and holman locomotives

M4 U diamond!

@hoiner why can't they build a normal locomotive

Awesome, I realy liked the Washington Model. But as soon as the puffy puffs started to puff out of it, I was just like, meeeeh... looks like a toy train. So thank you very much for the update!
If you need more inspiration for an American 4-4-0: As you already did 3 rather weird Camden and Amboy locos, maybe take a look at the Camden and Amboy No. 28.
https://cdn2.picryl.com/photo/2021/02/11/camden-and-amboy-no-28-4-4-0-b6d820-1024.jpg

I was wondering, so the density of the black smoke is also adjusted depending on the era of the train, thank you.