I remember the best ones didn't use "mesh" or foam, but instead used a series of spaced, conical inserts as sound baffles.
However, those are harder to duplicate, though I've tried using washers, and that seemed to work very well.
I've also used one of those "chrome lawnmower mufflers" sold at walmart, and home-depot. The ID of those is .75, and, oddly, work very well.
But thats all before the ATF went silly. Honestly, better off just using a HEAVILY ported barrel with a spool-type gun.