I have been putting off the DIY acoustic panel project for years. This was mostly because I didn't want to pay the ridiculous shipping costs to get the bulky panels delivered and had yet to find a local source. But I recently came across a local listing for some rigid Rockwool panels and went ahead and picked them up and now get this project is finally on deck. I think a good number of you here have dealt with this already so I thought I'd ask for some feedback on panel materials. I know the Guilford of Main fabrics are they typical goto choice. But I'm not a huge fan of fabrics that look similar to burlap. Although as I type this up I just jumped on their site and noticed there are many other different choices. I've read that many people suggest cotton fabrics over synthetics. But looking at the Guilford site I do see they list polyester fabrics in their acoustic fabric section. Many of the polyester fabrics offer more stretch so they would be easier to work. I suspect they would also resist fading better. I took a trip to a local fabric shop and the one fabric that looked good was 100% polyester. I held off until I could do a little more research. What advice might you all have? I am probably looking for a very dark blue or a very dark grey smooth-ish fabric.