Originally Posted by PapaBull
It depends on the type of tile how flat it will be. I've seen some very flat and quite true tiles available at Home Depot. As a base for leather, there will be some forgiveness and a perfectly flat surface really isn't necessary, anyway, in my opinion. As a substrate for anything but leather, I'd say perfect flatness is very important and even with leather, flat is good but the thicker the leather, the more minor variation is acceptable. Boards and paddles aren't flat enough to use for sandpaper but are plenty flat enough for leather.