Relatively straight-forward suggestion I think. More craftable ammo for the staff sling, similar to the ammo for the normal sling (clay, glass, steel, and lead).
It should also be feasible to throw acid bombs and grenades with the staff sling. Acid bombs could be used as-is, making them valid staff sling ammo is an easy json edit. Since grenades might explode while the player is aiming with them, and the charges used by timed explosives don’t seem to be compatible with the AMMO item type, the player could instead craft impact grenades using an impact fuse similar to the one in this video.