build the top of the box , put the sub in , use a flat screw with a nut on the back , have to predrill the hole to size tho since you won't be able to screw it threw the wood , use something like a ruber seal on the top end of the screw for a washer between the screw and basket , then put the nut and loctight washer on the back of the screw , put top of box on , screw it down , bam . only way to get the sub out is ripping the box apart. easiest way i know todo it. but then that can make it difficult to bolt the box down sincee you can't go through the sub hole , so you'd have to basically bolt the box down without the sub wall in.