Using a hammer to smash nuts on Shabbos: Ideal?

Hi,

On Shabbat, a utensil which is normally used for prohibited purposes is muktzeh; this is called "kli shem'lachto l'issur. However, one may use such an implement for a permitted purpose. Therefore, one may use a hammer to smash nuts, or a scissors to cut open a bag in a permitted way.

Ideally, one should look for a kli shem'lachto l'heter - a utensil which is normally used for permitted purposes - before using a kl shem'lachto l'issur. However, one need not go on an extended search and burden himself in order to find such a utensil.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 5:21:12)

Have a great day,
Mordechai