How are Hangul vowel letters constructed?

In the Hangul writing system, vowel letters are constructed using a combination of vertical or horizontal straight lines and short strokes placed on either side of those main lines.1

Beyond their structural composition, these shapes hold symbolic significance: they are designed to represent the Earth, the Sun, and the human. As a featural alphabet, Hangul is unique in that it maintains an explicit connection between the iconography of its characters and their corresponding pronunciations. When forming words, these vowel symbols serve as the nucleus of a syllable, typically following an initial consonant within a square block.23