title_body: How do I have Calibre automatically create a cover image from a non-ebook file?
upvoted_answer: I'm afraid this isn't the answer you need, and it's been a long time coming. Although I don't recall the method, be it via an add-on or whatever, I succeeded in using a jpg image of my own design (CS6) as a cover. It was available in the Calibre cover customization window, so applying title/author text in the usual way was no problem. So, yes, there's an easy to use method, and if I re-discover it before you do, I'll post the details.