This guy's friend offered to build him a subwoofer from scratch, so he came up with this design inspired from Super Mario Bros.
This is of course the question mark block and brick block seen in the original Super Mario Bros.! He built it to the correct dimensions and then I painted it. I am satisfied with how it turned out!
Turned out pretty awesome. The last time I tried building a subwoofer from scratch I ended up with a pile of broken electronics and catching my pants on fire.