Nothing like playing around for the fun of it. When I was a kid, I took an old factory door speaker, taped it to some glass mixing bowl of my mom's, and put it in a topsy's popcorn tin filled with clothes. The bowl acted as the enclosure and the clothes acted as a lowpass filter. I powered it with my sony boombox. Cost me nothing to make that sub and it sounded horrible. However, it was a step up from the shoebox sub I used.