I was thinking about putting together an offline internet-in-a-box, but nearly all of the tutorials are hosted on a raspberry pi or some other similar, fairly portable low cost device.
I was wondering if anyone has already set up a way to host one of these off a local NAS, with a frontend I could access via browser.
Each site you want will different. Wikipedia is …a wiki site. But, YouTube is a video site. Reddit is a message board. There are blog type sites. There are download sites, Google docs is highly interactive. All just different, a few may be the same-ish. And then, you can’t really fit the Internet on a box in your house. And the cost to host it elsewhere will be astronomical. Sounds like you have a few in mind? Find out what software they run, run it locally, and then download the site you can ant to mirror. You should be able to locate a crawler that will build the database(a) locally. Definitely legwork for a whole site/set of sites. Much easier if it’s a type of media: books, video, audio, PDFs, a database.
I’m not sure what OP is trying to create, but most Internet-in-a-box projects I’ve heard are trying to recreate text-centric sites offline (Reddit for example). I doubt they are trying to create an offline version of video sites, like YouTube. The size requirements alone make it unlikely.