It's easy peasy to make. All you need is jojoba oil (or some other carrier oil for your fragrance oil or essential oil). I used a 10ml container here - 7 -8 ml of jojoba oil and 2 - 3 ml of fragrance oil. I used a pipette with ml markings on it.
Thanks again for posting the recipe - Here's my try at making solid bubble bath. It's scented with cake, which turned it brown. It reminds me of coffee cake. All cubes have been used/passed out with much pleasure.