It occured to me that maybe the sub drivers could be mounted in open back guitar cabinets. They make either single twelve or dual twelve types. Now this look may not work for those w/ WAF issues, but I think it might be cool, especially as I already have guitars/amps/drums in my listening area.
These cabinets are generally made of dovetail jointed 1/2" birch ply. Would they be a solid enough mount or would they resonate like crazy? Maybe damped w/ BH-5 or the like?