Stuffed animals with a removable music box that’s baby-safe

Hi everyone
I’d like to crochet music boxes for a friend to celebrate the birth of her twins. They’re supposed to look like stuffed animals. The problem is that I’d like her to be able to wash them, but unfortunately the music mechanisms I want to crochet into them aren’t washable. Do you have any ideas on how I can attach the music mechanism to or inside the stuffed animal in a baby-safe way so that it can be removed/detached for washing?

I thought about buttons, but that wouldn’t be safe for a baby. I also thought about a backpack to put the music box in, but I haven’t found any patterns for such a small backpack yet, and I’m not sure how I’d close it either ...
I hope you have a good idea and can help me

Kind regards, Anne

I closed an opening with a zipper and sewed the zipper pull in place with a few stitches. For washing, those stitches can be quickly undone and then sewn back in place afterward.

By the way, there are also hand-washable musical mechanisms

Sewing it on securely is one idea. Do you happen to have a picture of how you did it with the zipper, or is it included in a pattern? 

Yes, I know there are washable ones too, but the mom-to-be was faster than me when shopping and unfortunately she had already thought of that???? and we can’t return them anymore, unfortunately. 

The question marks shouldn’t be there—that was a :) 

Unfortunately, I don’t have a picture of it, and I gave the music box away. It was a sewn rabbit. The belly was open, so I sewed the zipper in, closed it, and sewed the handle (there’s usually a little hole there) to the belly.
For a crocheted animal, instead of crocheting in rounds (i.e., turning the work over each time), you’d need to crochet in rows so you end up with a slit, something like this: Or you could leave an opening at the bottom that the music box fits through and sew the zipper in there.