Forget about the smooth outsides of “sarcophagi” in the Serapheum Lets assume you can get hordes of diorite rock chippers banging away for years.
But Try to hollow out huge “sarcophagi” with granite hammers and then achieve plumb sides, edges and squared corners inside. As well as finely fitted lids that form a seal?????
I don’t see how it could be done because there wouldn’t be room to swing a hammer with any force. And how many workers could you get into such a cramped workspace to hammer at the same time??/ Maybe some kind of acid might work??
Maybe someone could post a picture or two of those granite boxes.
The main mystery of the Serapeum is, since the stone isn't local to where it wound up (IOW, it wasn't mined en situ), how did they get the finished boxes inside there?