This is a stereo Quarter-Wave Speaker I designed in fusion 360. I am listing the speakers I used (bought in bulk at $0.48 each) and the Bluetooth amplifier I used ($13). For very old CRT tv speakers, this little thing puts out quite a bit of volume and the bass is actually pretty good. While my calculations of the wavelength are fine, the pathway might not be 100% optimal, but its very close.

Printed at 0.32 layer height for most parts, but the speaker cover/grill is 0.08 layer height. Everything is in Blue PLA and fits fairly well. I used hot glue to hold the side panels on (and to make it more air-tight).

https://www.parts-express.com/YDT613-68-2-1-4-x-5-Paper-Cone-Full-Range-Speaker-8-Ohm-77-289-2314

https://www.amazon.com/dp/B08Z3FBSDT/?coliid=I3ECBFZDC6LIL&colid=3OKL3BQJ2POP2&psc=1&ref_=lv_ov_lig_dp_it