( If this is already implemented in CSG tell me how to access it. )
Can’t really think of a good name to describe the feature I have in mind.
It’s essentially compliments CSG but it changes the color of the parts you selected and unionized.
I
Imagine a complicated shape already made and you want to add a yellow stripe through it, you get a part, stretch it out paint in yellow then do an action similar to Negating and unionize it with the shape and wa-la! It ads that stripe of yellow where the negated part was.