This idea of self-replication goes all the way down to DNA, thousands even millions of parts are self assembled into new DNA copied from a template. DNA, can itself through intermediate molecules, make proteins. This is fairly well understood.
But what about buildings or machines assembling themselves, is that possible?
As a movie lover, I immediately thought of the Terminator series when I saw the video below. You know where the computer becomes "self-aware," then all hell breaks loose. Machines make more machines and are at war with humans, is that possible? Maybe, watch: