As seen on X and YouTube:

Designed for use with a pair of the Dayton Audio RS100-4 4" full range drivers, and a pair of the Dayton Audio DS175-PR 6.5" passive radiator.  Suitable between 50Hz-18kHz.  (Sigma Studio DSP chain file included.)  Use reusable adhesive to seal around everything.  Apply 8 grams of additional mass to each radiator.  

Dayton Audio RS100-4:
https://www.parts-express.com/--295-378

Dayton Audio DS175-PR:
https://www.parts-express.com/--295-498

Dayton Audio KAB-250:
https://www.parts-express.com/Dayton-Audio-KAB-250v4-2-x-50W-Class-D-Audio-Amplifier-Board-with-Bluetooth-5.0-325-505

Dayton Audio LBB-3:
https://www.parts-express.com/Dayton-Audio-LBB-3v2-3-x-18650-Lithium-Battery-Charger-Board-Module-12V-with-Charge-Protect-325-201

M4 x D6 x L6 Threaded Inserts:
https://a.co/d/0w8jzpp

M4 Screws:
https://a.co/d/1DX5BYc

Switches:
https://a.co/d/8kIXpEo

2" Polypropylene Webbing:
https://a.co/d/2XBHqhl

Recommended printing settings:

PLA is okay; PETG is better.
At least 4 walls (perimeters) all the way around.
At least 20% gyroid infill.  (Higher is better.)
The radiator weights should be printed 100% solid.