Measure the sea salt, epsom salts, goats milk powder and sodium sesquicarbonate into the bowl. Take a 'lump' of refined or deodorised cocoa butter and grate 10g of it into the bowl with the other ingredients using a fine grater (if preferred grate into a dish and measure from there into the bowl). Mix these ingredients all together thoroughly.
Measure 10g of tapioca starch into a cup or glass and add 10ml (2 tsp) of your chosen essential oil or fragrance oil and mix thoroughly until the starch has absorbed all of the liquid, then add this to the rest of the ingredients and mix thoroughly.
Finally (optional) sprinkle a little complimentary dried flower petals into the mixture, mix in and decant into the 250g jar. Being this mixture is very dry it will keep for a long while without clumping if sealed in the jar.