Here is another idea. I wanted to make the boiling water effect for a cake of a lobster pot. I've heard of casting sugar on a silicone mat rubbed with alcohol. Just pour onto the mat and it will bubble up crazy. I didn't have isomalt to waste, to try out different methods so I thought of a mold.
I rolled small clay balls of different size and stuck them onto a mat creating a random pattern. Important detail, when you make any kind of clay figurine to mold, you want to go with a non-toxic SCULPEY clay, it says NON TOXIC on the box! When the pattern was done, I baked the clay, that takes about 10 min, and when it cools off its' ready to mold.
I stuck my pattern onto a rolled out Safe D Clay base, and locked it with my Adjust-A-Mold-Box. You don't have to use this box,you can make your own box (build walls of Safe D Clay) but if you make molds on a regular it's really great to have it!
Rubbed the whole surface with a little bit of Release Dit (the dits are really cheap and a little goes a very long way)
Mixed my copyflex and poured it. Copyflex takes 5 hrs to cure. Check out the results. I think it's fun!
This is the small bubble mold


This is what it looked like when I kept pouring isomalt and build it onto the top of the cake


Ready cake, lobster cooking!


Then somebody asked me to make a 12x12" to make the foam of a glass of beer cake. Also fun to use it for bubble bath cakes!