Actually this is a project which I started last year and was not able to finish it then.
Using WS2811 led lights (not strips) I thought about making a Christmas tree light being able to control every single led using an Arduino. This is actually very simple. For about 100 lights, I used a 10A power source just to be sure. Also next year I might add another 50 lights to it.
The best part about it is the programming. I found a lot of programs online. Took the nicest one, combined and tweaked them, and here is the result…