For my BIL and SIL I made covers for his tablet (Ohio State colors for him) and her iPad mini (pretty pattern for her). I used this pattern from the pinkpoodlebows shop on etsy.
The pattern was very detailed and came with different measurements for different eReaders. It is something that would be easier to work on if you have the eReader with you so that you can check to make sure it is fitting into what you're sewing.
But hopefully they work!