The good news is, it’s incredibly easy to make spa-quality DIY bath bombs at home. Let’s dive—or soak, rather–into it. However, you can buy it in its manufactured form (perfect for adding to bath bomb mixtures); just be sure to purchase a USP-grade, non-GMO kind. “I prefer versions derived from sugar cane,” says product formulator and founder of LOLI Beauty Tina Hedges. In addition to the magic fizzy ingredient, here’s what you’ll need for the perfect soak: