I created a bassport with waveguide for ported speakers.

This addition makes it possible to place speakers against the wall or give better spreading of the bass for down ported speakers.

The cone acts as a waveguide to deflect the bass away from one point, this way the bass is less muddy and speakers can be placed close to the wall if applicated on the back of the speaker instead as below as depicted.

Inspired by some high end audiophile speakers i owned (Fyne Audio).

I welded the parts together with a soldering iron but glueing is also possible.

Scale for your needs and the cone can be adjusted for your taste, just try it out en correct it as needed.