Stadler Form JASMINE Aroma Diffuser - White

What is the material the diffuser is made of?

Does this make a sound when it shuts off? Or when you turn it on, for that matter? So many beep and it limits nighttime use.

If you are happy with this diffuser, how big is the room you use it in? What kind of maintenance soes it require?

Does this diffuser have a light that stays illuminated while the machine is on?