This activity came about as a result of another activity that left me with some leftover paint. Not a whole lot, but I do hate to waste materials.
We were heading outdoors to play, so I threw the paints & some brushes into a caddy and grabbed an empty foamy soap dispenser and refilled it. I use about a tablespoon of palmolive dish detergent and then s-l-o-w-l-y fill the dispenser with warm water. If you fill it too fast it's going to foam up before you get enough water in and you'll have to empty it and start again. Don't do that! Also, err on the side of too little dish detergent because too much can clog up your dispenser and then it may be impossible to clean out and get it working again. I've ruined many dispensers that way. You can always add a little more soap if it's too liquidy. I haven't found a way to fix the dispensers I've ruined, though. (Let me know if you have a trick for that.)
I basically just turned my buddies loose with the materials without any instructions. They figured things out pretty quickly. This was a great multi-age activity too, I had children age 2 to 8 years old playing together quite happily.
One of the great things about this kind of activity is that it allows kids to be creative on their own terms. Without a lot of instructions, children are free to be creative and will often enjoy experimenting with their own artistic abilities. This is a great pre-writing activity, too, as the children make marks in the suds, with colours or just by brushing suds away in the same way we use salt trays.
I hope you'll try this one out and have some fun with it. Let me know what you think!