question #3 Sahih Muslim 501b, Book 4, Hadith 278 : What materials can be used as a sutra according to Islamic teachings?

The Apostle of Allah (ﷺ) set up (sutra), and Abu Bakr said: He implanted iron-tipped spear and said prayer towards its direction. Ibn Abu Shaiba made this addition to it:” Ubaidullah said that it was a spear.”