Got an idea for a gobo with front sheet of oc703 2" plus a sheet of 0c705 2", in a wood frame with back sealed with 1/2" ply, and a 1" air gap between the 705 and back. Question: is this just dumb? Figure the 703 will nab mids/hi's and the 705 may nab more low end, especially with a bit of gap in back. To use as a dual-purpose gobo: one side absorber, one side reflective. Intended to help isolate instruments in live recording setting.
You'll probably end up with a 4" panel that shares the properties of both types of insulation. The 1" air gap might help the bass a tad but sealing the back is going to block a lot of the surface area thereby minimizing its absorbing abilities. Nothing is stopping you from doing this but I'd probably want a separate absorber that's totally open and use another panel if I want a reflector.