Sounds like you are describing the Amish who have been doing this for a long time.
This is a good resource http://the-knowledge.org/en-gb/the-book/
The odds are so steep against you being alive to participate in such a future that investing time in preparing for it seems wasteful.
It's a good question and I have been thinking about it recently.
I think the biggest challenge is: if civilization does fall, e.g. due to a massive virus outbreak, and not enough people know how to produce industrialized products locally, it's going to be very tough.
So the immediately urgency is to bring some industries back.