Thanks! I realize the edges were a bit blurred; I did that with a Gaussian blur intentionally in hopes of making the walls look a little more natural. I hadn't considered a drop-shadow; that may well be the way to go. The space between the tiles comes from the size of the airbrush I used when tracing the grid lines. I was hoping for a mortar-like effect and even had some greenish mold in there, but it got lost in the black. I'll try another one later.