It's as if the "layer mask" comes in a preset shape that I can't modify—an archetype for all vertical lines rather than the representation of a specific line of a given length or width. By this, I mean that they don't form the shapes I want them to form but create separate masks around the salient features of each shape. Second, these halos only work for the simplest of shapes, like circles and lines, and quickly become fainter and more muddled when attempted for slightly more complex shapes like triangles and squares.