My goal was to add some type of blinker style, turn signal lights to my bike. The lights had to be removable and composed of bits & pieces from spare parts laying around the house. I'm hoping this servers more as inspiration than a step-by-step how to, your scrap pile of recycled glory may be different from mine.
Parts I used include:
Three (3) red blinky lights
You're going to need three independently controlled lights, one for each side and one for center. The center light is important. The left and right lights are much closer together than on a car and telling one direction from another without a center reference is no easy.
Two (2) toggle switches
A six (6) foot USB extension cable
Some scrap wire, zip ties, and other tidbits
Step 1: Lights
The lights you choose should be as simple as possible. Some bike lights can get rather complex with their multiple flasher functions and dozens of LEDs. The lights I found have three LEDs and a solid-strobe-off function button. The center light I'm using if the safety light already on my bike, the two others were cheap clip-on running lights.
We'll be leaving the center light alone for now. We want on/off control of each side light via the toggle switch we will be attaching shortly.
With the light on, open it up and poke around a bit until you find two contacts that turn the light off, there may be a pair for each LED or one pair that extinguishes them all, To each of these points attach a length of scrap wire and test. With the light turned on, you should be able to touch the wires together to turn it on and off.
Do this with both side lights and run the wires out a small hole in the lights casing.