Wandering, broken lines create a convincing stone wall texture, reminding the viewer of the stone pattern without describing every single block. Pencil guidelines are useful to indicate any strong horizontals to help keep perspective correct. Let the line wander a little and vary the lineweight to create an informal feel, breaking lines and leaving some unfinished to prevent an 'outlined look'. Where horizontals and verticals join it can look almost like a flattened tree, with branches and roots spreading outwards, but tapering off here and there.

