The Mixing Bowl is an alchemical apparatus that has the same use and effects as a Novice mortar and pestle. The mixing bowl can be found in a few caves in the Shivering Isles. It looks just like a normal clay bowl, so be sure to check any clay bowls that you find in dungeons. This bowl is an oddity and Una Armina will pay a sum of for it if taken to the Museum of Oddities.
Una claims the bowl is simply unusual, and not truly odd, but accepted it as a favor to the donor. She seems particularly displeased with the bowl, and pays very little gold for it.