While it takes some effort to get and to work with rigid fiberglass. It is the thing to use! I have done extensive research and used this stuff. Ethan's products are great. I have some of his absorbers. They are rigid fiberglass made into attractive, functional absorbers. DIY means less $, but you have to endure getting itchy for a day or so. You also need to have some basic carpentry/ assembly skills.
It breaks my heart to spend money on something that isn