Here is the projector system sitting in the soon-to-be-soundproof box. The box is an Ivar Cabinet from Ikea which I glued and sealed with silicone caulk. I researched acoustic foam solutions and decided to order this Convoluted Bed Pad. It's way cheaper than foam and I think it'll be dense enough to do the job. I'm also going to drill a couple of holes for cable feeds.