How to Build Acoustic Panels on a Budget

I decided to treat my studio with acoustic panels. At first, I looked into buying acoustic panels from a manufacturer but decided to build my own panels DIY style. The build process was easy. These acoustic panels are made of three basic parts. Something to absorb sound, for this I used 1.5" air conditioning duct board. A 4x10 sheet was able to yield five 2x4 foot panels. Second, cheap 1x2" boards from home depot for the frames of the panels. Last, something to wrap the panels with. Some people have used fabric, but I decided to use cheap carpet from home depot.
All in all, I spend about $150 for five high quality acoustic panels. I think it would have cost 3 to 4 times as much to buy these. Plus the project was fun.