You can make it out of anything basically.
I have a few made out of plastic and one made from the metal tip of a pen.
Also, they do other things besides quieting the hookah: http://www.hookah-shisha.com/p-1341-...-diffuser.html
I say yes, just don't buy it, make one yourself.
Also, if you check the Homemade section on the forum, you can find a few threads on home-made diffusers.