In this universe, an advanced race of aliens have constructed the largest object in the universe other than the universe itself, which is about 40,000,000 lightyears tall (don't worry about the massive amount of gravity this would have, it's reduced and managed through technological and magical means.). It is the shape of two 4-sided dice stuck to one another, with one of them being elongated by 2.5 times. It would look like a kite shape in a 2 dimensional perspective.
The surface has naturally developed landmasses, and the surface alone is enough to sustain most life forever, but that would require a daylight cycle, which is the problem. Due to the structure's non-spherical shape, you cannot make a ring of interconnected suns rotate around it. The light and heat energy must also come from the sky, not from heat lamps on the ground.
I have considered a sort of net of powerful heat lamps that encloses the structure, but that wouldn't work because it wouldn't allow ships to land and the maintenance would be a problem. I've also considered the aliens hiring others to operate massive "Space Trucks" that manually haul suns over areas at certain intervals, but that wouldn't work either because then it would only be a matter of time (no matter how many background checks you preform) until some lunatic steals a sun or crashes it into something important.