When I was living in Taiwan, one of the ways I forced myself to remember to pronounce the tones distinctly was by waving my hand in front of me, tracing the arc of each character’s tone.
It helped a lot even if I did look like an insane expat conducting an invisible orchestra.
One more thing: there's quite a bit of variation in how regional accents in the mainland can affect tonal pronunciation. It might be worth reaching to some native speakers to give you some baseline figures.
You'll love Mike Laoshi: https://youtu.be/cna89A2KAU4?si=SQEZ_0ooO1z119_k
For accents, I’ve mostly tested with a few friends so far. I’m wondering whether region should be a parameter, because training on all dialects might make the system too lax.
This sounds like how solfeg training works. You use a hand signal to indicate a specific tone: do re mi fa so la ti
Hand motions help! Especially when you want to memorize new words, because initially you need to treat tone as something additional to remember.
I used simple index finger motions to mark tones.
In a university Mandarin class, one of the adult students (i.e. probably 40 or so) WAY over exaggerated his tones, to the point that the little old lady teaching us laughed out loud after one of his answers.
A few years later, he had the most clean and consistent pronunciation out of anyone I'd been in a class with, and easily switched between the Beijing and other accents depending on which teacher we had on any given day.
I rather regret not emulating him, even though I haven't really used it for nearly 20 years and have forgotten most of it.