Colored Pencil Gimmick

Following the release of the kids' magic pack and one of its effects, the Colouring Book, I remembered I've been trying to make a gimmick but haven't been able to get it right. So, I put it aside for a bit to clear my head, hoping that when I pick it up again, I'll have some fresh ideas 😅 lol.

The gimmick itself is a box of crayons or colored pencils, the kind with an opening where you can see the colors, like this:

After a wave of the hand over it, the colors vanish, and then, magically, they can be transferred to the Colouring Book so that the drawings appear already colored.

I've made several versions, but either they don't look good because the gimmick is noticeable, or you have to be super careful so the pencils don't reappear, or it just looks super cheesy and isn't worth using 😔.

I'm not sure if I've explained it well 🤦🏻‍♂️, but if anyone has any ideas on how to make this, I'd really appreciate the help 🙏🏼😊.