A rotary device may include: a binding unit detachably coupled to a part of an external object and including a side surface defining a geometric plane and having a length through which a longitudinal axis extends； a stationary unit positioned adjacent to the side surface of the binding unit and formed integrally with or coupled to the binding unit； and a rotary unit coupled to the stationary unit, the rotary unit including a first end and a second end, the first and second ends being opposite one another, the first end being rotatably coupled to the stationary unit, wherein the rotary unit is rotatable between a first position where the rotary unit forms a first angle with respect to the longitudinal axis and a second position where the rotary unit forms a second angle with the respect to the longitudinal axis, wherein at the first position, the second end of the rotary unit is a first distance from the geometric plane, and wherein at the second position, the second end of the rotary unit is a second distance from the geometric plane, the second distance being different from the first distance.
