I have made some absorption modules (you know, rockwool and chicken
wire) and covered it with Dacron (to keep the rockwool particles
inside). Sounds good, looks godawful. I understand burlap is the
acoustic best fabric to dress it up with.
Unfortunately one can't get hold of that in the Netherlands. I know
this sounds strange but it's true; I'm at the end of a six weeks quest
and still: no burlap in any nice colour. Any foreign
postorder/internet companies that do coloured burlap? The weave must
be fairly course to allow sound to pass thru it without resistance.

Thank you for your time!

Beste wishes,

Ignace