The paint may add extra thickness to your gears, potentially creating friction. Does anybody have experience with painting gears and what effect does it have on friction?
Please do not paint your gears, or anything that regularly makes contact with another part of the robot for that matter. This will add excess friction to your system. You can dye gears any way you’d dye any other plastic. https://www.ehow.com/how_8550306_dye-plastic-rit-dye.html
If you still feel compelled to paint your gears, you can also tape over the teeth and paint only the outside.
It will add friction and cause problems to your gears. I suggest IF you do paint to simply put tape over the area that makes contact with the other gear.