Duct muffler...DIY?

I have been looking at quiet a few DIY Duct muffler guides...
Most are like this http://buymarijuanaseeds.com/community/threads/diy-inline-fan-muffler.138045/
my favorite is http://billpentz.com/Woodworking/Cyclone/MufflerBelliveau.cfm
And then I go to the local grow store and look at a phresh muffler and the damn thing is a tube with egg crate foam glued in it....

Whats the best/cheapest/most effective way to build one of these...
is it better to do the egg crate thing or go the full 9 yards and make multiple layers?

In my younger days as a guitarist, we lined our practise room with egg boxes (only the side used to hold the eggs) and it worked great.