u can get polyfill from pillow shop. or razaar (quilt) makers. ask them for polyester sheet.
yes, your box has little depth, so chance of falling. did you plan on fastening it to the base with T-nuts??
by the way, i hope you have not made a hole in the box to connect the wires?? use a speaker terminal strip. dont connect like ur last box was connected. box should be totally sealed.
and dont install the sub for atleast 18-24hrs after applying silicone. it can eat away the rubber surround and other rubber parts of the sub..
you can use some makeshift t-nuts made out of regular nuts and bolts maybe?? although velcro is the best, but difficult to find in pakistan.
