Every disc has to share the same outer diameter, and each crescent should be constructed by overlapping two circles of that size rather than drawn by eye. Phases built independently end up with inconsistent curvature, which is obvious once they hang in a row. Spacing between discs matters almost as much as the shapes.
How many phases should a wall set include?
Why do small stars fall out of a cut panel?
What material suits celestial wall pieces?
Do zodiac and constellation designs need accurate star positions?