Hi @Joni,
you should take a look at this Third-party Fairphone cases (eg flip, folio, etc) and this Poll: What case do you use for your Fairphone + Experiences topic. Lots of cases are being discussed there.
There’s one manufacturer mentioned, who offers sleeves made out of microfibre(?): weebag
So far, no one found an official flip case, but people tweaked some other flipcases to fit their phones. Again just take a look at the already existing topics 
Edit: Almost forgot the obvious, the official FP case is not made of wool/leather, it’s plastic! Not sure if that’s what you’re looking for though, but you can find it in the shop.