Although a variety of treatments are available for commercial use, they tend to be quite expensive. After some research both online and in print, we came across several sources for DIY acoustic treatments using rigid fiberglass panels and simple frames. These are often referred to as "bass traps," although the ones that we're focusing on have a fairly wide rage of absorption. While commercial versions are available for almost $100, we were able to make these panels for about $24 each.
We can not take credit for this design, but have combined several people's ideas into a step-by-step guide. Most importantly, we give credit to Ethan Winer's excellent article, Build a Better Bass Trap.
For more information, check out the good folks in the acoustics forum at recording.org
Step 1: Plan your setup
For our room, we decided to build 12 panels. Since it's a room for music recording, we can take down some of the panels when we want a more lively sound, or we can put them all up when we want a more controlled sound. IMPORTANT: a "dead" sounding room is not natural, and causes the ears to fatigue much faster than in a typical space. Since the point of this project is to enjoy music sound MORE, you want to avoid too much absorption.