I used a little Eleksmaker 2.3W laser running 1500 mm/min, 90% power, and 300 dpi or so for dark etch, using flat-white paint. For light etch, I use black paint (tempera or matt-black spray) and slow to 1000 mm/min, with all other settings the same.
It’s all described in that thread but please know that all lasers are different and you need to test for optimal settings using your laser and paint…