If you want a directional light, such as was prototypical from the 1920's on, then this lamp is for you. This is so different from typical LED lighting used on layouts that tends to splay light out over a broad area. This Swan Neck lamp, sometimes called "Gooseneck", would be the most commonly seen light on streets up through the 1950's and even beyond.
The Swan Neck Lamps come in packs of 3 are scaled to be equivalent to 18’ (6m) in height. That is they are ~3" tall, but can be sunk into the layout to create a lamp that is 2 to 1/2" tall.
They are suitable for HO layouts as well as On3, On30 and S scaled layouts, measuring 4" from the bottom of the stem to the top of the arch. To match it to your scale height - adjust its insertion it into your layout. For HO leave 2 to 2 1/2" above.
These are easy to insert - just drill a 1/8” diameter hole in the layout and insert the fiber through the hole and then the base of the lamp, which will be a snug fit into the 1/8” diameter hole. Then insert the fiber beneath the layout into the Lamplighter box. Each lamp comes with 4’ (~1.3m) of 1mm fiber optic to allow easy placement in proximity to the Lamplighter box. If the height of the lamp needs to be decreased, just insert it further into the hole in the layout.
These lamps are made from thin walled metal tubing and fiber optic cable.
To change the ambiance / color, add a drop of translucent paint to either end of the fiber. If you add it to the end of the fiber that is inserted into the Lamplighter, then make sure the paint is dry prior to inserting the fiber into the Lamplighter box. See the video on how to do this. To create an old world look, I use the Tamiya X-26 Orange Translucent paint, however, you may use whatever paint you like or even a colored marker.