I have taken a empty speaker box, de carpeted it.then cut it in half . took the working speaker woofer has a decent rubber surrond(6 Ohm) from a dead paramax im3 junk home Theater radio, and added a few of my own items, more magnets to the speaker and a reinforced the dented center cone i used a hard plastic bottle bottom. cut it sanded all edges painted inside cap black and used two glues ,super and strong plastic and paper glue to glue over the existing cone. painted glues black.sanded and painted the new cabinet black used the chrome feet off the broken paramax i glued internal sound pad to the cabinet then used a thick fluted plastic cup with the bottom cut and sanded for the yellow porthole. connected and hot glued speaker wire to terminals and hot glued and screwed the speaker terminal cup back in place mounted the speaker and tested it out . also noted this box was from a carpeted dual 8 inch woofer with the middle partition and was already pre tuned for a 8 inch speaker i changed no inner dimensions beside the 3 ,1/2inch by 3 inch magnets. finished project sounds very deep and has a great tone.By passive i mean really, a non powered with no amplification sub/ woofer. that could have all the low frequencies sent to for deep bass. i sourced all the parts free, the carpeted box from a recycle drop area. the broken paramax im3 was being thrown out by a friend because the amp panel was burned out. not sure by what but i wasn't going to try to repair the paramax because of its known as the cheapest parts you could use..but took it home looking to take any capacitors or resistors out of the panel for salvage. and as i was about to get rid of some stuff in my garage area. i thought of this and began with the idea !!! all the tools and glues i already had. tools used were a reciprocating saw. a handheld belt sander, and the egg foam from a old craftsmen toolbox. the port is a thick plastic funnel cup cut and sanded out the bottom.
the speaker cone is reinforced with the bottom of a thick soda bottle cut sanded and the inside painted black and glued over the existing center cone.
also three 1/2x3 inch magnets were glued to the existing magnet.
project took a little over an hour with the exception of letting the paints and glues to dry overnight.