DIY acoustic room treatments

Looking for some advice on do it yourself acoustic room treatments. What products work the best? Thanks

I am currently using diffusers made up of egg crates, burlap cloth, and 2" X 2" wood constructed as a rectangular frame. It works best on taming the back wave out of my ESL speaker panels. It also made the bass sound a tad cleaner. I positioned them directly behind the back of the panels (on the back wall about 2.5 feet) from the speakers. I also positioned one behind my center channel speaker for my HT applications. Maybe you can experiment on this and hope that it will make a difference on your system.

Make sure that you optimized your speaker placements on the room too, before considering treatments. IMO, this is what other enthusiast neglect to spend time with. Proper speaker positioning will surpass any other room treatments that you may consider as far as immediate "impact" is concern.

Hope this helps
jon risch stuff is well designed and has a great following on the asylum web site
My speaker placement is good. I'm trying to work with the sound reflection.
You know, I made some of the Jon Risch tube traps (16-inchers) some time ago and they worked to great effect. When I moved, I decided that they were looking a little "gamey". I auditioned some retail traps, the names of which will go unspoken, but I largely preferred the Risch results, so I returned the retail units and simply recovered the DIY's and added solid wood top caps with some homemade inlay work and now they both look and work very nicely, indeed.
Owens corning makes ridgid yellow inulation board.Two feet by four foot.Wrap it with some discount fabric and you are set.Remember To absorb(velocity absorbers)sound above 500khz material has to be four to six inches thick.Russ H of stereophile mag says eight inches (WOW).Go to google and punch in diy bass absorbers(pressure absorbers)there are a couple I'm going to try.A balanced room is a happy room.I don't know of a single sub that can't use a parametric eq to smooth out room modes also.If not thats all you hear is the mode it's self.