Some people have the tradition to hanging a Magen David in their Sukka. Perhaps the six sides allude to the six “Ushpizen” guests who visit during the first six days of Sukkot: Avraham, Yitzchak, Ya’akov, Moshe, Aharon, and Yosef. The star as a unified whole symbolizes the seventh “Ushpizen” — David — the “king” who unifies the whole. Furthermore, the Magen David has 12 sides: David as king unified the 12 tribes.
– Topic: A Six-Pointed Question: The Origins of The Magen David, Ask the Rabbi, Ohr Somayach