Print slow and steady. Inspired by this video:
https://www.youtube.com/watch?v=cXIaGfhAO24

It's a voice training tool, often used by singers for SOVT exercises, which is where the pressure in the vocal tract above the vocal folds is increased by restricting outward airflow.

The TL;DR is that it,s not automatic it just it makes light and bright sounds easier to make and heavy and dark sounds harder, you still need to put the brainpower in for it.

They come in 2mm-8mm inner diameters, each 1mm apart. Print slowly, tall thin objects like this suck (molten layers, detached prints). There's a mouthpiece hopefully to make it more comfortable to hold in your lips. They should all be about 13cm long, as I saw quotes for strawphonation about working with 5" long tubes (this is just for predictable pressure reasons, longer tube = more backpressure, narrower tube = more backpressure too).

Start with the largest, as it will get more difficult as they get smaller. Drinking straws, coffee stirer staws and cocktail straws all work too, I just wanted a variety of sizes and things that are less disposable.

OpenSCAD file included if you want to make adjustments. It's really quick and dirty.