The SHulchan Aruch paskens that a shofar is a kli sh'melachto l'issur on Shabbos and mutar l'tzorech gufo and m'komo. I was wondering why it is not muktza machmas chisaron kis since we would never use it for any other purpose.
I saw that the Shmiras Shabbos quotes Rav Shlomo Zalman Aurbach Zt"l who makes this point. B'zman hazeh a shofar would be muktza machmas chisaron kis. It was only in the days of the gemara and Shulchan Aruch where they used it for other purposes that it was considered a kli sh'melachto l'issur