Endon's Silver Mold (or Curious Silver Mold if it was retrieved before the quest) is a quest item for the Thieves' Guild quest Silver Lining. Endon requests that the dragonborn retrieves the mold for him as it was robbed from the Khajiit Caravan by Rigel Strong-Arm and his/her group of bandits on its way to Markarth.
Location
It is found in the treasure room at the end of Pinewatch Bandit's Sanctuary, surrounded by various gems, ingots, ore, gold, a coin purse and two Silver Candlesticks.