I'm working to compile a list of great modelers selling goods and services like the following list. You can view the latest version here: https://www.steves-trains.com/post/resources
Here are some examples of modeler services I'm trying to compile. Send me more at: https://www.steves-trains.com/contact or in the comments.
Custom Weathering and Graffiti Work
They Make It Like That: http://theymakeitlikethat.com
Pro Scale Models: http://www.proscalemodelsco.com
Gavin Faivre: https://www.fiferhobby.com/fhs-weathered-cars/
Layout Design Work
Journal of Model Railroad Design: http://www.jomrd.com
Layout Vision: https://www.layoutvision.com/design
Shelf Layouts: https://www.shelflayouts.com/design-services
Rail Dreams: https://raildreams.com/about/services/
Bob's Track Plans: https://www.bobstrackplans.com/
Layout Building Work
Stephen Lamb: http://slatrains.com/
Shelf Layouts: https://www.shelflayouts.com/design-services
Rail Dreams: https://raildreams.com/about/services/
Rasch Studios: https://www.raschstudios.net
Laser Cutter and 3D Printer Files
DIY and Digital: https://www.patreon.com/diyanddigitalrailroad/shop
Watch the full video below, including a quick look at a weathered and graffitied CN boxcar and four dumpsters I picked up from They Make It Like That.