To build this, you will need the following (prices in Canadian Dollars):
1- Two Rear flashing bike safety lights: $10.50 each
I used Blinky7
lights from Planet Bike. I got them from Mountain Equipment Co-op here in Canada. Probably REI in the US would have the same thing. Important: The lights must have a blinking mode, and the blinking must be sustained when the batteries are removed, and put back in. The lights I used have a capacitor that slowly discharges. This means that if I don't use my turn signals for 20 minutes, the light gets reset to a solid light and I have to press the switch on the light to set it back to blinking mode. Ideally, your light will have a switch that will remember the blinking setting indefinitely.
2- One AAA x2 battery holder
: $1. Get one with a case to keep the batteries dry.
3- One Double Pole Double Throw (or DPDT On/Off/On for short) switch. $5.50
I picked up both of these items at Lee's Electronic - my goto shop for electronics in Vancouver. Probably Radio Shack would have something similar. My battery case has an on/off switch, but that's not really required, as the switch will be used to turn them off. If you can find a waterproof switch, that would be ideal.
4- Wire. Red and Black. 6 feet of each should do, or enough to go from your handlebars to the just at the top of the seat stays
and back. 26 gage or so should be fine, but anything reasonable will work.
5- one extra long screw that will fit the nut of the Blinky mounting setup.
6- a little silicon
, similar to the stuff that you would use to seal around your bathtub. Caulking, Shoe Goo, or Goop will also work.
7- A little strip of adhesive Velcro (both sides)
8- Solder and a solder iron. Or you could use silver conductive epoxy if you don't have access to a soldering iron.
9- Xacto knife
A set of helping hands (the mechanical device, not another person), and a set of wire cutters were also used, but you could get by without them.