Use PLR articles and connect the articles with some appropriate text in between to connect the articles with some appropriate text in between. For example to connect 2 articles you could say something like "In the next chapter (article) we'll discuss....." You could even compile an ebook using articles from free article directories, but bear in mind that you can't sell this ebook and have to give it away free.
Get plr articles in the same niche on same or different keywords depending on how you want your layout of your ebook.
As a reader, I hate it when books say "In the next chapter..." That's what the table of contents is for. But you're right, you could take some PLR articles and make them into an ebook. The best way is to use an article pack of 10-20 articles written on the same niche and by the same author. If you put random niche articles in your ebook without thoroughly editing, you'll have continuity issues. The pages and chapters won't flow.