Blocks that are available in a different color on each side (design)

Hi.
I have often encountered problematic designs, which you can not perform, because each solid block has a full color, and if you want to build a wall which on each side will be a different color, it can not be done in the thickness of block 1, and you can not design a block that changes color.
I suggest inserting a new table (I have no good idea what to call it) where it will be possible to insert 2 blocks with full color, and get from there a block that is half of each color, which will be divided between right and left, but later also between top and bottom will be very cool.
It will be possible to do it between wool / concrete colors or even between any two solid blocks.