@Harrison: Sure i could use commercial lights, but that would not be a DIY project. That's the fun of it. Trying to create every single component.
I had solder every wire on the led (2 wires of each), solder 1 resistance for each 2 leds, and in the end program the arduino to flash the lights as i want. This part is not finished yet.

@Demon: the real thing, sure, that will for the next year, i pretend to do it on a real size tree, but this time i will not use my own leds, i will just buy the commercial ones, something like 30 in a row, but i will buy 6 or 7 sets, and then remove all the electronic they have, and program them as i wish.

Arduino is really a nice board. This one the "Nano" cost me 7 dollars only including chipping !!