I made a nice brown(ish) noise generator for my bedroom. I use it at night and sometimes during the day when I want to meditate, or something. It uses an ATtiny85 to generate white noise, which I filter through a resistor-capacitor. I put it in a mounting I made and used varnished balsa wood to make a nice box for it.

ATtiny85 are dinky little chips to use.

It's instant-on and off, and I don't have to worry about corrupting anything, or some upgrade quirk like I do with the RPi. I was still using my original RPi on a permanent basis until recently. RPis are not obsolete if your requirements are modest. Try running X-Windows and Firefox and you're in for trouble, though.