I was serious when I told you that this is easy. Honestly, the hardest part for me was finding vegetable glycerin, and that was only hard because I realized at the store that I didn't actually know how to pronounce it, and I wasn't keen to ask the sales associate where it was. (Side note: it's gliss-er-in. You probably already knew that. The sales associate certainly did.) It was also kind of hard to choose which scent of castile soap to go with. I decided on almond, but keep in mind that if you have very sensitive skin, you should probably buy unscented or even the "baby mild" kind.
Once you've gathered the homemade bubble bath ingredients, all you have to do is pour and mix them together. The water and castile soap will mix well, but the glycerin may settle at the bottom of your container. That's normal!
To use your homemade bubble bath, first give your jar a gentle shake, just enough to mix in the glycerin. (Don't over-shake - it'll get foamy and too bubbly.) When it looks less separated, simply pour an eighth of a cup of the liquid bubble bath into warm, running bath water. If you find that's not enough, keep adding in small amounts until you've reached your desired bubble level.
Recipe by DIY Natural at https://www.diynatural.com/homemade-bubble-bath/