I am building mine out of 2x4’s and 1/4” plywood. You could also do 1x material but I have 2x scrap I can use for free. I’m going to paint the window side black and wrapping the room side in black velvet but you could finish it however you wanted.
7.1.4 Theater Room (In Progress): JVC-RS46U, Silver Ticket AT 2.35:1 142”, Onkyo RZ830, Anthem PVA-7, Panasonic DBT-110, JBL Studio 270’s, NXG-NX BAS 500 (for now)
3.1 Living Room: Samsung 64” F8500 Plasma, Anthem MRX 300, Dynaudio Audience 52’s, Dynaudio Audience 122C, NHT SubOne