I've been toying with the idea of building a speaker cabinet with sort of semi-hollow plates, for example like this: Cut 12mm particle board to size. Perforate it with a tight pattern of ø30-40mm holes, leaving just the edges, handle mounting areas etc. solid. Sandwich the perforated board between two 3-4mm plywood plates, all glued together. Holes may be filled with wool or something. Make all six plates this way, and assemble the cab. Roughly calculated this would reduce the weight of a box with about 30%. Anyone tried something like this? Any thoughts on how it would work?