To dam a star, to enclose it completely, would require the construction of a Dyson shell. Humans can shroud a star with a swarm of bodies, a Dyson cloud, but we cannot forge a sphere. Instead we approximate one by surrounding a star with thousands of ringworlds, all of similar size but with no two having exactly the same diameter. We make a discus and then start tilting, until each ringworld is encircling the star at a unique angle. The light of the star rams through the narrowing gaps as the ringworlds tighten into their final orientation. Shutters close on a fierce, deadly lantern.
