Battery operated would be ideal. I had one years ago but can no longer find it! Same size and shape of a cassette. You placed the cassette on it and pressed the button and it got rewound, then turn it over and rewind the other way.
I also had a manual one (also since lost!) This had a bunch of gears in a circular housing with a handle on it. You inserted it into the hub of the cassette and turned the handle. I seem to remember that one was made by Tandy.
The Maxell ew 340 was more what I had in mind.
I could send you an image of it if I could fathom out how to do it!
This is what it looks like.