Twin Reflex Camera LED Light

First step is to take off the top of the camera, or the viewfinder, unscrew the top four screws
Next step is to put copper tape on the two parts of the inside metal that touch when the viewfinder is open, This will act as the switch. One will go to power and the other will go to ground.   

The next step is to add your button battery connection to positive (Red wire) to one side of the two sides
 

What I did next it to create my LED parallel wiring, Make sure that ground is soldered together and the positive sides are soldered together with wires, Also, make sure that you heat shrink the live wire.
 

Next I found the best way to connect the ground sides together was to use conductive thread.
I connected the thread to the other side of the top viewfinder with copper tape and then put electrical tape over the thread.

Then the thread gets tied to the positive side of your LED lights I used heat shrink for extra protection, so it doesn’t fall off

In that same photo the ground is also connected and soldered together.
At this point you should have a whole connected circuit. When you life up the top viewfinder the switch should activate and the LEDs should turn on.