This railway signal light is made using the real (Dutch railway) signal lights as ref.
It is scaled 1:32 (1 gauge, 3/8 inch scale)

It is designed to hold 5mm Led lights

With lights and a nice paint job it looks like this: https://www.youtube.com/watch?v=KG0F4u03Xn0

The dwarf signal-light can be found here (https://www.thingiverse.com/thing:3918207)

Meer info op: Spoor+1+Sein