Quiz

If a polygon is not flat, then the intersection of all its sides is impossible, because a straight line intersecting two of its sides lies entirely in the plane of those sides and cannot intersect sides lying in other planes.

A plane is a set of points. Each point can have its own color. If the points are combined into solid areas (which can only happen by chance), then the boundary of the areas can be... Any color, and not necessarily the same.
I will try to process Uranus's answer now.