I have one that I make up for a few spa clients in big ziplock bags. It does bubble a bit because of the slsa but you could leave that out. Its really basic, I use course pickling salt first, add the fo and colour if you like, mix that around well so the course salt is taking the moisture, I then add sea salt, mix that well by that time there isn't any moisture left. I then add about 1/4 cup cornstarch. Its a nice soak.