Can someone use material to hold together a tallis (e.g safety pin etc.) that cannot itself make a kosher tallis?
The Mechaber writes that clothing whose corners are leather (a material not Mechuyav in Tzitzis) while the rest is from cloth, is Mechuyav in Tzitzis, and the opposite is Patur.
The Maggen Avraham writes that this is because we look at the majority of the cloth's makeup.
This Halachah is based on the Mishnah in Kla'im, which says that regarding Shatnez we judge a cloth by its majority. (I recall seeing this Mishna mentioned in the MA but can't find it now.)