this was an old project from last year that i keep finding myself using over and over. my husband is a sound engineer. he needed to have sound-absorbing panels to change the acoustics of the room he was recording in. we went shopping for some studio-foam panels and wedges.. but they were REALLY ugly. so... with my leftover AMH fabric we made our own sound absorbing panels, that i thought were better suited to the apartment.
ingredients:
*soundproofing / sound absorbing foam material. (note - this is the most important consideration in the project, after much debate we went with the 80% recycled echo absorber sound absorbing baffles: http://www.soundprooffoam.com/echo-absorber-baffles.html that being said - there are a lot of neat products on the site that i think have potential such as the quiet door absorber and other wedges / ceiling tiles.
*very thin plywood squares cut to the desired dimensions or you can use sturdy cardboard. consider finding some cardboard in nice condition and just re-use it.
*cute fabric
*tons of pins
*hot glue gun
*copper wire
Step 1: create a plywood / cardboard template that has the desired dimensions that you want (mine are 2 ft x 2 ft) and use it to cut the other backing material to the desired dimensions. use same template as a guide to cut the sound absorbing baffles with a SHARP razor blade / X-acto knife. if you want to remove a step but pay more money - then just pick out the pre-made sound absorbing tiles in your preferred dimensions.
Step 2: assembly: lay the fabric out over the backing material and baffling to cover. this is where the advantage of cardboard really counts because you can stick pins in place right through the fabric onto the cardboard.
Step 4: use hot glue to glue the fabric in place over the cardboard / backing. remove the pins after it cools.

Step 5: cut little pieces of wire and curl both ends in a spiral with a peak in the middle - use this to hang the panels on the wall with very small nails. alternatively - you can try to use velcro to attach to the walls, however, i had mixed success with that method.
ideas:
sound-absorbing panels have multiple uses. obviously the primary reason for these is that my husband moves them around the room where he records music to change the acoustics, but i absolutely love them too. we recently moved to a larger apartment with wood floors that had a horrible echo. the echo is gone now that the panels are in place. but keep in mind that if you have wood floors you really need a few carpets around to help with the echo as well.
you can also move these panels around for easy decorating options. if you have a bunch of them you can also create a giant mural on the wall.