I made these this weekend... they were so easy to make, and plus the ingredients are really easy to find. These are fizzing bath melts, and I put them in a Jell-O "jellybean" mold- so they're butter beans! The term's not original, though I halved this recipe and got 60 beans.
-170g cocoa butter
-80 mL sweet almond oil...actually any oil would work (roughly 16 teaspoons)
-200g baking soda
-100g citric acid (i had a pretty hard time finding this, but it should be near the canning aisle of the grocery store)
melt the cocoa butter over low heat, remove when melted, and add the oil. let cool, but make sure it's still a liquid. add color and/or fragrance (a little note about fragrance- these smell really good without fragrance because of the cocoa butter, but if you decide to add fragrance, i think that a creamy smell would work best. i used eucalyptus, and they smell good, but chocolate and eucalyptus isn't the greatest combo.
) Mix the baking soda and citric acid together in a separate bowl and make sure that there aren't any lumps. Once the cocoa butter has cooled, but is still liquid, add the baking soda and citric acid mixture. Spoon the mixture into molds and let them cool (pop them in the fridge if you want).
put them in a warm bath and they'll fizz and melt