When my son and I started developing the 3D folded paper Magen David a few years ago we thought it would be welcomed by secular Zionists. Later we thought that it fits as a decoration for Sukkoth, but we didn't know that there's a deep connection between it and the tradition of the Sukkah Guests (Ushpizen, or Ushpizin). I found it only today while I was immersed in searching articles about the origin of the Star of David . That's how I stumbled upon an answer of one of the rabbis in Ohr Somayach Yeshiva (I didn't find his name on the page). In it there was the following excerpt about the Ushpizen:
"Some people have the tradition to hanging a Magen David in their Sukkah. Perhaps the six sides allude to the six "Ushpizen" guests who visit during the first six days of Sukkoth: Avraham, Yitzchak, Yakob, Moshe, Aaron, and Yoseph. 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".
In Hebrew I read that the origin of the Sukkah Guests tradition is in the Zohar, Volume 3 (Leviticus) Parsha Emor, 103, pp. 2) and it started in the 16th century by Kabbalah sages who composed a special greeting for the guests.