- Buy some glycerin soap at a craft store.
- Melt it in the microwave, add food coloring, and our into a mold, such as an ice cube tray.
- You can also add essential oils if you want them to be scented, though most people find that unnecessary for bath crayons.
- They will take about an hour to cool completely, then you can pop them out of the mold.
And voilà... you have bath crayons!