> You'd need extremely small scale factories that can build everything needed for a modern civilization.

It's not as much as you'd think, specially if you can survive on the first couple of decades with regular shipments from earth, mostly for very advanced materials and electronics.

A lot of manufacturing capacity in our society is redundant and focused on non-essential items. In addition, some manufacturing processes are complex because of the scale of our society but could be made simpler for a small colony, especially if you are not worried about details or finishing quality and approach it from a more utilitarian perspective.