>>207899This is what you need. It has how to make just about everything in any environment. There is another book whose name escapes me on how to build a machine shop from scratch.
Also, like another anon said, it would have to be secret. Careful initiation rites would have to be performed to confirm an applicant's competence and dedication and they would finally have to swear and oath of secrecy. Outside interaction/supply trips would have to be closely monitored and perhaps run as night ops (since mostly all we'd need is scrap metal and stuff from junkyards). It would have to be treated like a ninja clan or the like.
For drones, all persons would need to dress in at least earth tones and all signs on recent activity/construction would have to be hidden.
Perhaps underground would be best.
I personally have gardening and survival skills, as well as martial arts, weapons/armor making and military architecture knowledge (useful because mad max). I've always thought it would be fun to be on that 'The Colony' tv show, but they probably wouldn't let me because I'd be too tempted to seriously hurt/destroy the 'hostile outsider' actors.