If you go with the non-disposable wash mitt, they already make cute washcloths for kids that you put your hand in. No sewing needed! We have a duck one, it's almost like a puppet. I don't do soap, but would there be a way to liquefy your soap, soak the cloth, and let it dry? If you sew something together, it would be real quick to just to a quick seam along the outside. You don't really need to put a thumb in it. You could do bunches at the same time. Sounds like a fun experiment! Can't wait to see how it turns out!