- Tracing the circuit using 3M copper tape
- Choosing a "plus-rail" and soldering the leds accordingly.
Testing the leds on a lab power supply and determining the total current through the circuit.
(In one particular case, two different colors were wanted, which made the circuit a bit more complex: two circuits with different currents, from one power brick :-))
- Determining the voltage of a discarded power brick and finding out the needed extra resistors to get the right current
- Mounting the power brick and a finding a way to lock up the incoming cord