Visible to people who have questions about the file structure of calibre, hold mistaken opinions about any reading device equaling (let alone surpassing) the Sony PRS-505, or demonstrate anything except complete antipathy to DRM, anyway.
Whether that sub-category of MR members will be a viable market for book covers is another question entirely.
Mostly, if I start making book covers, it will be an excuse to do some leather tooling, which I haven't really done in a decade or more. "I have to take over part of the dining room to set up a workbench because I'll, um, sell some stuff. Really."