if you know Homeworld or the first Dawn of war game, you may know what I want to suggest.
The current building editor has many single colour patterns but only a few multicolour pattern with a very limited colour set.
My suggestion is that there are only pattern and you can choose the colours(colour set) you want to use in those pattern.
You know the left side and my idea is to change this current system an make
the wooden wall pattern changeable to build a wall with the same pattern but maybe in blue and red.
or the road
from the light brown coulors to gray
This would give us unlimited freedom to build the stuff like we want it to be build.
I do not know is this is even possible but I wanted to suggest it while you are working on the new Building System.