Unless you go the customized route for decals, you can purchase N scale decals to help decal your rolling stock, bridges, buildings, or locomotives. I usually find my N scale decals at train shows. There is always someone clearing out their N scale decals of what they have left or will never use.

 This is Micro trains Line SD40-2 Santa Fe model which I customized with working ditch lights.

Micro-Trains Farmers Co-op Build by Modelersguild.com

I am definitely getting better at Z-Scale. Another Micro-Trains kit, I am liking these more and [ ... ]

Scratch building is defined in Wikipedia as “The process of building a scale model "from scratch", ie. from raw materials, rather than building it from [ ... ]