Several ring binder manufacturers have started making traveler’s notebooks and Hobonichi covers, Van Der Spek (Nomad TN cover and Codex Hobonichi cover) and Gillio (Giramondo TN cover and Appunto Hobonichi covers) among them.
Apple Pig on Etsy is another seller offering ring binders. This artisan is extremely innovative and uses zips in many of his designs, which is not something you see very often with TN makers. He also cuts v-shapes into his credit card slots, allowing you to get the cards out easily by using your thumb, instead of pulling the slot or card outwards to get the card out.
These particular horizontal zips allow you to slot in a TN insert snugly. Lin is also very good at accommodating custom features, so the magnetic closure could be replaced by an elastic or a clasp, for example.
At the moment only available in A5 size, I would be really interested to see if they come out in smaller sizes at some point. This binder can be made in any of the leathers that Lin stocks.
And a video showing all the features