Halfling skulls.
They're a versatile bunch.
This.
My elven alchemist took a rank in craft: glass blowing... so each bomb is a custom made artistic work of art glimmering in the light as it sails through the air bringing pretty shiny doom to all of his foes.
like hour glasses with different liquids in each section that cause the explosion (or other effects) when mixed together in a violent matter (aka hitting a target!).