I've made them - use the book as a pattern, lay it out so you have a turned edge allowance top and bottom, with additional length to add a fold over pocket on both front edges - the dimensions will depend on the size of your book. Then you just bend the book cover backwards to slip into the pockets. Placemats make an easy cover for small books. I finish the edges of the pockets with a cover stitch (or even just a pinked edge) so there's no extra bulk between the cover and the pages.

Even with a pattern, you still have to custom fit for the size of your book. Did you ever make paper covers for your text books? Same concept.

Actually, I did a search and found a few instructions on-line - search on "sew removeable fabric book cover" - They're easier than it looks.

Here's one, more on e-how: How to Make a Removable Fabric Book Cover for a Journal or Notebook | Anjie's Blog

 

Perfect - thank you - should be able to manage that

 

I just posted about this! I used a pattern, IJ883 by Indygo Junction.