I've started making a glass block window, and I am very pleased with the progress so far. It looks like real glass, and the surface is wavy like the real deal, too. Next up will be figuring out an approximation of a hopper vent (the tiny window insert that allows for airflow).
As you know, I freely share nearly every process when I make things with very few exceptions. This process is one of those exceptions, so there is no tutorial or materials list at this time.