A very beautiful Christmas tree can be made if desired. And it is unlikely that anyone else will have one. You can even give this device to someone. The principle of the Christmas tree is quite simple.
I will not bring you boards, circuits, microcontroller firmware, because I believe that this design is complicated for repetition. But you can simply do without it by connecting the LEDs to the power supply through the resistor. Of course, you can do without a board and solder the frame from copper wire with a diameter of more than 1 mm. Generally think for yourself.
I will introduce you to the principle of operation: LEDs with a microcontroller are mounted on the board. The microcontroller serves to smoothly switch LEDs between rows and reduce attenuation during a break. In general, how do you program ... The whole thing is connected to power - a battery like "Krona".
Further, all these gadgets, by any of the convenient methods, are attached to the moving part of the 120 mm cooler from the computer.
Turn on the power on the board, apply voltage to the cooler. We admire the Christmas tree made by ourselves!