Although this kind of lights are found in any store now, making one's own is quite satisfying.

The circuit works from 12 V power supply -- this goes to the strings of LEDs (4 in each string). The LM 7805 regulator makes voltage equal to 5 volts for the oscillators, so the frequency is not affected by supply voltage.

There are 4 strings of 4 LEDs, each string is its own colour (Red, Yellow, Green, Blue). The LEDs are driven by 2-transistor constant current sources (more info on them: Currents through LED strings are adjusted so all colours are mostly the same brightness to eye.

Here is the circuit, annotated:

Multivibrators have slightly different frequencies, so the blinking patternt changes over time.

Video of the circuit operating:

This simple project took me less than a week from conception to completion, quite a refreshment from the last one.

Hope someone will be interested and maybe makes something similar.