At first I thought the main problem would be finding a ring mechanism, people wouldn't want to wreck one of their existing Filofax organisers just to get a set of rings, with the possible exception of an Apex!
- Bensons - US company selling a variety of ring mechanisms
- Loose Leaf UK - UK company
- Prefs UK - UK Company
So it might be feasible to make or have made an organiser to your own design. But before the legal people at Filofax start sharpening their pencils... I don't think they need to worry about us going in to competition with them with an aptly named Philofaxy Organiser... just yet!