I remember reading somewhere that spherical enclosures are ideal
shape..is that correct? debatable?
Incidentally, I live in India where we get *Very Cheap* earthen pots,
called "matkas" which are near perfect spheres with 'mouths emerging
from protruding necks', used for storing water, and they keep the water
inside cool (as they are porous I guess).

I wish to build a speaker enclosure using them, as they are ready made
in various sizes, have an artistic appeal and if the sound reproduction
dose not suffer, It's a very attractive proposition!
These pots or "matkas"  have walls which are usually 3-4 Milimeter
thick ( I can get them made thicker).

I did some tries by mounting 8 inch drivers on the "mouth", did some
stuffing inside using polyfill, but the observed sound reproduction did
not seem too "right" to me- I thought it was resonating too much (like
booming) at low freqs. and had a tinny feel to the sound..

Please have a look at the setup here:
http://www.geocities.com/madforeagles/DSC01343.JPG
http://www.geocities.com/madforeagles/DSC01344.JPG

My queries are, should I line the insides with some material to make it
air tight? how thick should I get them made? should I  use the same
volume calculations for 'normal' enclosures for a driver? should I
stuff it with Polyfill?

Thanks!
Suraj