Abstract: An apparatus and a method for mixing a substance such as tattoo ink or nail polish may comprise a rotor rotatable about a fixed axis, one or more holders on the rotor for receiving a container containing the substance and disposing the container perpendicular to the fixed axis, and a motor for applying a force to rotate the rotor around the fixed axis at less than about 120 revolutions per minute (RPM). The method may comprise receiving a container containing the substance into one or more holders on a rotor, in which the rotor is rotatable about a fixed axis, and applying a force to rotate the rotor about the fixed axis at less than about 120 RPM.