I LOVE THIS FLOOR.
I constructed it with authentic used bricks, grouted with spackle, put on some gray grunginess, then sealed it with a matte varnish. It did not take as long as I suspected it would. The only thing I wish I had done differently is stir a little gray paint into the spackle before I grouted.
Because I knew I would want to manage the randomness I made a decision to not look at any brick I grabbed from the bag. It was a great opportunity to practice self-discipline. Even when I grabbed the sixth (gulp!) light brick in a row, I just glued it down next to the previous one. I am quite proud of myself.