Do you know that you can paint all sorts of colors and pattern on bath bombs to make them even more unique and beautiful? You can mix mica colors with rubbing alcohol to create your liquid paint. Then, using small brushes, you can paint this onto your dry bath bombs. Snowman face? Sure!
Micas can be sourced from many online stores like this one: https://www.brambleberry.com/micas-c46.aspx
Here is a tutorial: https://www.soapqueen.com/bath-and-body-tutorials/painted-rose-bath-bomb-diy/