some glue (I prefer strong gel type, dries in 24hrs)
a cr2032 3v button battery
some flux / rosin will help soldering on the metal of the pin
and of course a soldering iron with some solder, and other tools….
The copper tape on the legs of the peg conducts electricity from the battery to the LED. Notice that I use the metal of the spring to conduct the current too, by putting the copper tape in one slot under the metal spring. The battery has a positive and a negative side. Often the positive side is marked with a ‘+’ sign. The LED also has a positive leg (long) and negative leg (short). By sliding the battery the positive side connects to the copper tape on the leg, closing the loop, which conducts the current to the leg of the LED. You can check if the LED works by pushing the battery in between the legs. If it doens’t work try to put the battery the other way around in between the legs of the LED. That way you can always find out which size of leg is negative or positive.