One of the most difficult parts of crafting a convincing eldritch tome is the hardware. What grimoire or book of forbidden knowledge is complete without all kinds of little buckles, corner protectors, embossments, and decorative inserts? Unfortunately, that kind of metalwork is almost impossible to find today. That's where Closure, a blog about making metal book clasps, bosses, and book decorations comes in. There's an amazing variety of work on display and many of the posts include a detailed rundown of how the hardware was constructed.
Sadly, it appears the blog hasn't been updated since April, but there's still a wealth of useful material available.