This is a remix of Hexibase's fantastic 3D printed subwoofer using a Tang Band W3 1876S 3" driver. I wanted to print this design in one piece rather than gluing it. So I copied Hexibase's original design in Fusion 360 and made some tweaks. I've included the F360 archive, so you can customize it yourself.

Summary of changes:
-Prints in one piece
-Slots for holding captive M3 nuts
-Surface pattern showing internal layout
-Integrated supports for chamber and driver cutout
-Optional holes for M3 threaded inserts

The design relies on supports for the chamber roof and the speaker cutout, I created integrated supports which work well without using much material. If you prefer, you can generate supports in your slicer in stead. It took me about 15mins to carefully remove the supports with some pliers and flush cutters. To me, this is preferable to having to print in two halves and glue them, but I'm sure that is a matter of opinion.

I changed the waveguide cross section to come to a peak rather than a rounded top. (I changed the height slightly to keep the cross sectional area the same.) This creates a 45 degree overhang which prints fine without supports.

I created a kind of vaulted ceiling above the chamber to give a nice airtight wall with only a small fraction of the area directly supported. I have provided versions of the file with and without integrated supports.

The terminal cut-outs are sized for these binding posts:
https://www.amazon.com/gp/product/B01LYA4YDP

The surface pattern can be emphasized but swapping filament color a few layers in (Prusa Slicer makes this very easy.)

Note: this prints in one piece, but depending on your settings, it will typically weigh well over 1kg, so most people will have to change filament part way through.

I put in four holes for threaded inserts like these:
https://www.amazon.com/gp/product/B00Y20YLKY
There are STL's with and without the inserts.

I also created a test print, so you can print just the chamber section, to check the supports are working for you before committing to the whole print.