to the question: is the Magen David symbol appropriate as an adornment for religious items?
-the Magen David is an ancient Jewish emblem, and is therefore entirely properly displayed in synagogues and on religious objects.
This blog (by Zeev Barkan) is dedicated to the Star of David, its history, its various meanings and usages in different cultures. It includes thousands of pictures of Star of David, six-pointed stars, hexagrams, Solomon's Seals, Magen Davids and yellow badges,and served as a resource for three books and four art exhibitions.
Haifa designer Hayim Shyater took this photo of an advertisement where the Star of David gives the hat patriotic meaning and makes it interesting

Charlotte Halle wrote in Haartz on April 12, 2007 about stamp collector Lawrence Fisher from Ra'anana, Israel who collects stamps across the Arab world some carrying anti-Israel messages like an Iraqi stamp issued in 1983 commemorating the "Aftermath of the Zionist Racist Aggression on Sabra and Shattela," depicting blood dripping from the Star of David and a fist with blood coming out of the ground…
