The Pocketbook ‘flip cover’ that works with the InkPad Color 2 and 4 might work with InkPad Color 3 as well. I asked a question about it and someone with IPC3 said it ‘fits perfectly’. I’m a little skeptical, since the dimensions aren’t exactly the same.
https://www.amazon.com/PocketBook-Re...s%2C257&sr=8-3