Here is mine that I did, do you mean something similiar to this? if so that baffle board (cover piece) is a .25'' thick board. I believe it is cedar wood but it is sold at both Home depot and lowes. it comes in like a 4x5 board. I took cardboard and got all the curves of the trunk and transfered it to the wood. I put the cover piece over the box and then put the subs in. Then I put the screws into the sub that went through the cover board and into the mdf box which held everything together. I have a link to the worklog if you need it.