For modelers working in O Gauge, which includes 3 rail Lionel and American Flyer there is a collection of Swan / Goose Neck, Carriage and Globe lamps together with a range of fibers and connectors, and 2 different sizes of lights sources, the Lamplighter™ boxes.
The Lamplighter boxes come in two sizes, the Lamplighter 2 which is the larger of the two, is the most suited for O Gauge work owing to the typical size of fiber that will be used and noting that this box provides 30% brighter light than the Lamplighter 1 box.
The best fiber to use with this gauge is the 1.5mm fiber as it provides the brightest light, especially for lighting buildings. Each of the pre made lamps come with 3+ft of 1.5mm fiber. The other fiber diameters will provide correspondingly less light, but may be suited to applications such as lighting cars, trees, etc.
If there is a need to connect fibers together, there are Fiber Connecting kits that are suitable for connecting 1.5 to 1.5mm, and 1.0 to 1.0mm fibers. They can also be used to connect different sized fibers together, such as multiple 0.5mm fibers to a 1.5mm fiber. This is useful when lighting small objects such as car lights using 0.5mm fiber but then running a 1.5mm fiber back to the Lamplighter box.
What to buy for a first order:
A Lamplighter 2 Starter Kit which will include 60ft of 1.5mm fiber.
Add lights now or later. Add different size fibers to experiment with.