I had a look at Kikosattic on Etsy today and Akiko has 12 binders for sale. She makes each one by hand:
The binder is totally my hand made, hand cut (no cutter, only knife), hand stitched. No machine is used at all. It’s more complicated than it looks as the binder actually consists of 22 pieces of leather and lining parts plus ring parts.
All edges are filed, trimmed and polished.
As far as I know they are all pocket-sized and fit Filofax rings. Akiko is a binder user herself and still has her first-ever Filofax.