sosatheshark
+1y
if you dont have enough air space you can always use polyfill,,comes in 1 cf bags usually at fabric shop ,to seal it up properly just resin the inside real good ,and use chop matt .99% of the time people do sealed for glass sub boxes ,and in truck you can make them sound just as good as wood ,not as low as ported but ,they look great ,and can sound great here are a couple of glass pics i have of sub boxes,these are older ones ,but sounded great ://i414.photobucket.com/albums/pp228/sosatheshark/bubbasbox.jpg