It’s possible to spend a lot of money on a leather notebook cover but why do that when you can get a beautiful cover from Davis Leatherworks for less than the price of a fancy bottle of ink? You won’t find any covers more beautiful than these no matter how much you spend.
The covers are designed for Field Notes but I use them with my Calepino notebooks just fine and I’m sure they’d fit any similarly sized notebooks without any problems. They’re simplicity itself: a single piece of leather with one elastic band to hold the notebook in place and one to keep the cover closed when not in use. This simplicity is part of their charm.
I could write more but the photos tell a better story than I ever could. Suffice to say, these are some of the most beautiful things I own.