A rotation mixer including a housing, a drive unit coupled to the housing, a carriage mounted on the drive unit for rotation relative to the housing, and a basket mounted for rotation relative to the carriage. The basket receives material to be mixed. The carriage includes an arm and a drive line coupled to the arm. The arm is mounted on the drive unit for rotation about a first axis relative to the housing, and the drive line converts rotation of the arm into rotation of the basket about a second axis relative to the arm during use of the rotation mixer. The drive line illustratively includes a belt and plurality of pulleys upon which the belt travels in a continuous loop, the belt engaging with a gear on the basket to cause rotation of the basket.