Homemade bath crayons:
Buy some glycerin soap at a craft store. Melt it in the microwave, add food coloring, and pour into a mold. I used an ice cube tray. You can also add essential oils if you go for scents, though I find that a bit unnecessary for bath crayons. Takes about an hour to cool completely, then pop out of the mold and you have crayons!
Will the food coloring stain?
No actually it doesn’t. I sometimes drop food colouring into the water of the kids bath, a green or purple bath is way more fun that plain old clear, and I’ve never had a stain on the bath, or on the kids. You’ll possibly get stained fingers when making the crayons but food colouring eventually washes off.
I have never had any trouble with staining. Purple water for a princess is always appreciated