First I took a short strand of fiber optic and heated one end with a lighter to make it round like a bulb.
Next, thread the fiber optic into a short piece of hollow alumimun tube. The tube was cut at a 45 degree angle on one end, and once the fiber optic is inside the tube, I form a 90 degree bend.
The mast target is created from a peice of styrene cut out using a hole punch.
The target is slipped over the tube and glued in place.
The top of the mast is painted black. Here are several signals ready to be installed.
I use bi-polar LEDs to light the signals. I drill a hole in the end for the fiber optic strand.
Here I am testing a signal by holding the other end of the fiber optic over the green LED on my computer keyboard.
The LEDs are wired to a Tortoise switch motor to change polarity when the turnout is moved. This motion changes the signal from red to green and vice versa.
Here are two working signals on the Rocky Mountain Sub model railroad.