Funny square brush.
(updated) I accidentaly didn't check if my tablet driver was acting ok when I published this originaly so some of the brush settings were wrong. Only just realized as I decided to use it after resetting my tablet drivers and clipstudios tablet settings ^^' This should have the correct settings.
You just draw with it it's pretty straight forward.
It will pick up your main and secondary color in the brush texture, this doesnt work with secondary color selected, only main.
Old version