Abstract: A personal massager for sexual stimulation including a rotational drive, a mechanical transformer coupled to the rotational drive and which transforms a rotational output of the rotational drive to provide an output drive shaft having increased torque relative to the rotational output of the rotational drive, a mass coupled off-center to the output drive shaft, and a housing within which the rotational drive, mechanical transformer, and mass are disposed and which includes space for rotational movement of the mass by the output drive shaft, wherein the rotational movement of the mass imparts an oscillating motion to at least a portion of the housing.