So, I saw this idea on youtube and had to try it myself on a book with a skinny spine. 
The fabric is tea dyed and from mums leftover when she got curtains and pillow casings sewn. I love this fabric, especially how it turned out after tea dyeing it. The inside isn't finished yet. Not sure what to do with it. I made this today because of questions that turned up in a 'sketchbook revival' facebook group challenge (the green book I blipped some days ago...) I'm participating in. Those not used to cutting out a book block from a hard cover can sometimes cut through the spine itself and I made this as an extra option, instead of mending the cover with fabric, or discarding it and begin again.
It's been snowing all day so It'll be interesting to see if 1. I get to sleep tonight or if the snow ploughs will be working, and 2. if the busses go as they shall tomorrow. I do have a bit of time between my busses and I have time to walk from the bus stop to the building where the meeting's held.