Have a garden railway (think outdoor electric trains)? Decorate it for the holiday season.
We did some digging and found a great example of using 5MM LEDs on the train trestle. Look carefully for how the LEDs are packed tightly together using large zip ties (touch the image to the tight). Think straight lines outlining key features of your setup.
The key is using really small lights to try and keep them as close as possible to the scale of your railway. 5mm LEDs are pretty small and certainly look better than using giant C9s.
Be sure to add small twinkling lights to other parts of the railway landscape. Add a dusting of some sort of snow covering and you have a Christmas scene that will dazzle everyone as the trains wiz by.