The Flat Colored Blocks mod exists, yes, but they don't have that type of flawless solid color that is appealing for "infinity" type rooms... you know, like where the entrance looks like it's floating in an infinite space because the walls have no shading or texture. Those types of blocks are amazing for creative, sci-fi builds. I originally saw an item like this - lapis caelestis caesicius from ExU, but since that is outdated and the block was from a version 3-4 years ago, that one isn't an option. From what I can tell, there isn't really anything like that on the mod market, or not that I could find. It would be great if it could actually become something at some point for creative types.