Q. Hi, I wonder if it would be OK, halachically right to use a golden cross and melt it to make it into a Magen David necklace? I was thinking about the golden calf that was destroyed and it’s gold not reused, and I suspect it might be avoda zara to do it.
Kol tov,

A. Objects used as a deity or an idol are forbidden in benefit. This is derived from the verse written with regard to the property of the inhabitants of an Ir Ha’Nidachas: “Nothing shall remain in your hand from the banned property” (Devarim 13: 18 – Rambam H. Avodah Zarah 7: 2)
Horav Shlomo Miller’s Shlit’a opinion is that if the cross was seen and served as an idol itself and was worshipped as such, it would become prohibited in benefit. However, if it was only a symbolic object, representing another deity, it would be permitted.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a