A system is provided for creating a modified analytical model from an existing analytical model and CAD data of the modified model to reduce the workload in creating geometric and analytical models. A pedicure spa can include a basin having an embedded light aperture on a first interior surface of the basin. Wherein any one of the planet gear and the input gear has a boss being coaxial with the center of the other of the planet gear and the input gear, and the other of the planet gear and the input gear has a groove in an elongated hole shape which the boss fits in. An angle of a vertex of the bend is within a range of 40\xb0 to 85\xb0 inclusive.