Laser cut parts with amazing detail. As in lots and lots of parts, including some very small ones which the people who make it say they'll replace (once...) if you lose or break one.

I reckon this will take me months as an evening after work isn't going to be enough to complete most of the numerous steps, but looking forward to the challenge.
People who make them are called railmodel.co.uk - never heard of them until I miss-typed this forum address into my browser.