A rotating mechanism comprises a retaining plate having a cut-out defined therethrough, the cut-out is curved; a rotating plate being capable of rotating in a plane parallel to the plane of the retaining plate by a shaft extending through the retaining plate and the rotating plate; a pin rotatably affixed to the rotating plate and slidably engaging with the cut-out to guide rotating movement of the rotating plate when the rotating plate rotates around the shaft in a plane parallel to the plane of the retaining plate.