Galen didn’t construct the DS, only the laser.
Then how did he construct a convenient way for the rebels to destroy it???
That’s a common misconception. He didn’t. All he did was make an unstable reactor to set off the chain reaction. That’s why he wanted the rebels to steal the plans, so they could figure out on their own how to set it off. He didn’t have a clue how the rebels would do it. It’s entirely possible he was expecting an espionage mission than a bunch of snub fighters trying to make a one in a million shot.
So it would have been possible for, say, a 4 person crew to infiltrate the Death Star and sabotage the faulty reactor using the Death Star plans carried by R2? It’s a good thing there was never the chance for such a sabotage mission or the Rebellion wouldn’t have needed to give away the position of its base and send almost all of its fighters to their destruction.
😉