Good luck! I've been wanting one but....
I used to be a draftsman back in the early 70s, pencil and paper. These days if you want something 3D printed you either have to find a file already available or design it yourself.
I've tried designing a couple of simple things using FreeCad and I just don't have "the want" bad enough to learn. I think the actual printing would be a piece-o-cake but the design part, not so much.
I read about this college kid up around DC that had a small 3D business going and saw some of his work, impressive. He was doing train parts in HO, S, and O scale. I do O scale and emailed him about doing a project for me. He has already done one in HO and said it would be no problem to do it in O scale.
Here's the model he sent me, 18" long (3 sections glued together):
View attachment 71133
All he had was purple filament. Here's the finished model:
View attachment 71135
And one variation of the real deal (engine went thru a number of mods over the years):
View attachment 71139
Anyway, it's just incredible what can be done with 3D printing, I just wish I had it in me to do it.