Weigh out all of your ingredients. As with any soap-making project, precision matters here — a kitchen scale will be your best friend.
Whip the soap base. Using a hand mixer, beat the foaming bath butter until it transforms from a dense blob into something light, fluffy, and almost mousse-like. This is the step that gives the finished scrub its signature airy texture, so don't rush it.
Add the fragrance oil. Pour it in and mix again until fully incorporated.
Add the mica powder, a little at a time, mixing until the color is even throughout. Stop as soon as you're happy with the shade.
Fold in the sugar. Mix until every granule is coated and evenly distributed — the mixture will thicken slightly and take on a beautiful, cloud-like texture.
Place into your containers. Transfer the finished scrub to a jar. Add a little swirl on the top, this step is entirely optional, but it does make for a prettier finished product — and there's something deeply satisfying about it.