"why companies don't want to use them is a question with a infinite amount of answers. most of them are financial and political.
mostly its the price of helium that sinks the projects. if we find any helium it will be free as well as any material you find.

Im not saying that this is the first thing you should attempt in a apocalypse. you will need to have almost all the basics set before attempting something like this. you will need a stable power, water and food supply before considering something like this. And one should not ignore the kind of morale boost a project like this could be. a successful colony could attract survivors from the surrounding areas making your population go well beyond the hundred. They will need a project large enough to keep them from fighting each other."

"time is not a problem either since zeppelins have the advantage that they can be expanded. even if you just manage to build one cell it will still fly and be used for lifting things. if you attach a balloon with a lift of 10kg to something weighing 20kg you will have split the power needed to lift it by half. after a while you will have another cell ready that can also lift 10kg that can be used for marking where you are so that new survivors can find you (if that is what you wish).
after you have built enough cells you might be able to lift a person when the weather allows it. You now have a lookout post and can look for signs of life that could indicate the return of society or just plan a escape route in case of emergencies.
after additional time you will have enough cells to carry a person and additional supplies and that is the point where you can attempt to travel in order to expand your knowledge in aerodynamics as well as getting additional material by going to scrapyards. with the additional material gathered by the one man zeppelin you can build a 2 man zeppelin and increase range as well as safety.
the key is having the things you do useful in you other projects even if you can make it the size you need to have it fly to another settlement.

This is why I think it is the most plausible AIRCRAFT you can build on your own. That is why I started this thread because a apocalyptic event is the only time where zeppelins are more useful than any present aircraft. companies and military dont use them or even explore the possibility because they have reached a point where they can make even more implausible things.

You could have spent some time thinking all these things up and solve even more details. But that is clearly not what people do here."

"*Gives PedroAsani a bear hug*

But you forgot to mention Hangar because you will need to protect it during its down time."

"That's what I wanted to hear. The reason I talked about tremedous resorces is the sheer amount, not that all people won't need smaller portions of them.

And about scrap metal: it is doubtful you will find it in the right curve, angles, joints, and thickness to make a blimp: now what?

And, specifically, what type of fabric are you planning on? How are you going to get it?"