Rusin Helix

A Rusin Helix is a megastructure of a curved, close-ended helix, in the shape of a ring or torus that orbits its host star.

Design
The curved helix orbits its star in a ring-like fashion, similar to a ringworld but instead of a straight band its coiled into a helix. The helix alone cannot rotate about its central axis because corkscrew motion needs a linear axis, and in this case, the axis would be curved. The hexagon as can be spotted at the low left corner and along the helix can be seen as a kind of foundational holding piece. Each of the six facets along the helical path could hold a series of sliding plates that run along the helix. These plates could move in succession along the helix until they eventually fully orbit the star. Half its time would be faced away from the star and the other half toward it. The plates would be incremental and be short enough so as to not follow a curvature. For instance if one could find perfectly level ground on earth, maybe a salt flat for instance, and build a floor that was fifty acres say, that floor would not hang off the earth if it did not follow the curved path. Why? Because the curvature of the earth is virtually absent relative to the floor. If you were to make the sliding plates small enough relative to the helical curve then they could successively slide across the curvature without issue. These sliding plates would move across the foundational holding piece at a particular rate, each three-hundred sixty degree rotation is roughly twelve hours of travel time. The plates would slide along like train on railroad tracks. One could put incremental, successive O'Neill Cylinders inside the hexagon's path of helical curvature to maximize surface area and again account for curvature by ensuring the the Cylinders are short enough. A number of other uses are possible such as hydroponics, arcology, or other uses. If O'Neill Cylinders were to be used, then artificial light is necessary, in that case one might prefer that every other facet collect energy from the host star in order for the lighting within the hollow region of the helix and to feed energy to the plates sliding across. This helix would itself follow a path of curvature into a ring or a torus perhaps with a very small diameter.

Benefits
Strands of the single, double, or triple helix would provide ample surface area for habitation. The facets of every strand will have diurnal and nocturnal cycles based on the speed of the successive plate rotation. So there could be three separate collectively rotating stands and two sides used, therefore a triple helix could provide six different facets that all have diurnal and nocturnal cycles, three facets of which are faced toward the star and three away. Likewise, a double helix would always have two strands, two facets interchangeably pointed at the star while two are pointed away. This would provide a significant improvement over a ringworld because a ringworld has one side that is forever fixed towards its host star and one side that is perpetually shrouded in darkness. The ringworld would also require a separate structure to block light from its host star to create night or "nocturnal cycles." And unlike the Alderson disc, the helix would have far less mechanical stress, would be far more sizably practical to build, and would not require a thickness of a few thousand miles, a surface area which is subject only to the sweltering heat of the star or the frigid depths of space. The helix could make use of all its area.