Pam B I just use bubble
I just use bubble powder. (it’s cheap enough and even comes in colors) Just a few grains will give tiny bubbles. the more you use the bigger the bubble. When a small amount is mixed with fine frit it also looks great. You can get uniform bubbles by creating a grid with stringers or thin strips of glass with a clear layer on top. bubbles will form in the small empty squares. You can exagerate the bubbles by putting a few grains of bubble powder into each empty square too. It is definately something to use sparingly I learned that the hard way.