For a chain of 3 StarLights, you will need:
1 2xAA battery case
Battery Clip (PP3 clip)
15 3mm LEDs - 5 yellow, 5 red, 5 green
3 10ohm resistors
2.5m red wire
2.5m black wire
Step 1: Do the math, test the circuit...
V = 3 (supplied by battery) - 2.2 (forward voltage of LED) = 0.8
I = Combined current required by the LEDs = 0.02 x 5 = 0.1
0.8 / 0.1 = 8ohms of resistance
I tested the maths on the breadboard, and thankfully, it worked!
Step 2: Create the stars
Give the star a second or two to cool down, then flip it over, using the bluetack again to hold it in place, and repeated the process for th negative legs, pushing them together and soldering into place.
The process was repeated with the other coloured stars.