ordered thin (1in) t-channel aluminum frame parts from mcmaster (similar to bosch framing, but cheaper, link) and other stuff to build a nice acoustic enclosure with access from all sides. Bought the 1/4" plexiglas parts for the lid from drillspot (much cheaper and free shipping). For the side panels i'm thinking about using thin aluminum panels mounted to the outside of the frame (not in the slot) and then using the full depth of 1in of the frame structure for acoustic damping using a combination of sound absorber-barriers, rubber foam, lead, mass loaded vinyl/Nitrile closed cell foam or anything else. However, putting it in the slot would be easier. Didn't buy foam and stuff. Will wait for the frame being on the table to see what to do.