[ebpjoocq] The Death Star is realistically buildable

Use a Nicoll-Dyson beam powered by a Dyson swarm around a star much brighter than the sun, e.g., Deneb.  Either focus the beam and precisely aim it from afar, or just drive the star, swarm, and beam generator to the target with a Shkadov thruster, the latter also requiring no technology we don't currently have.

Star Wars's Death Star's hyperdrive is unknown technology requiring unrealistic science; its superlaser is not. This proposed Nicoll-Dyson beam is certainly not the size of a small moon; it has the mass of a large star and size of a planetary system.  (It's a Death Star, not a Death Small Moon.)  However, "giant sphere" is a roughly correct shape for a structure built around a star.

Moving a star with a Shkadov thruster unfortunately takes millions years which has both the problems of keeping the generations of crew focused on the task for that long and bright stars with their short lifetimes might go supernova before reaching the target.  In fact, it might even be a challenge to build the Dyson swarm within the lifetime of any star with energy output high enough to vaporize a planet in a few seconds.

So this superlaser is probably not practical as a weapon, but it might be useful as a toy: blow up nearby planets for fun just like they do in the movies (recreate the effect, as the Mythbusters do).

Inspired by Isaac Arthur.