Bag of Energy Bullets (3.5e Equipment)
From D&D Wiki
Bag of Energy Bullets: This brown leather bag is inscribed with a rune representing different types of energy.
This bag produces sling bullets imbued with a specific element. 5/Day you can produce a bullet that does an extra 1d4 Damage of either Fire, Cold, Electricity, Acid, or Sonic in addition to its normal damage.
Moderate (DC 18) conjuration;CL 9th; Craft Wondrous Item, Leomund's Secret Chest, Acid Splash, Ray of Frost, Electric Jolt (Spell Compendium), Burning Hands; Cost 1,250gp, 100 XP, 3 Days; Activation: Free (manipulation); Weight: 3 lb.; Market Price: 2,500 gp