❡ This is a Plugin for the Glyphs font editor. It superimposes the current shown glyph as a rotated copy of it self. This can be pretty helpful when working on symmetric characters (e.g. [0, O, o, S, s, Z, z, X, x, …]). The degree of a desired match depends on each design, of course. It is not nessessary to match the drawing with it’s rotated counterpart, but it can indeed help to balance letters in matters of weight distribution and/or optical centering.
Find more infos about it and get it for free: ☛ here on GitHub. ☚