I had difficulty getting the oil to form circles, for the oil were dissolved by the water, I tried with olive and sunflower oil. But after experimenting with different amounts of oil so it was easiest to get circles when it was only a few teaspoons of oil in the water, in the beginning I poured in several tablespoons and then it's just got thick and had a lot of small bubbles.
To get the colors to the image I lifted up the bowl and then just simply add different colored paper, foil and other colorful things under it and then i highlighted them by two small spot lights from the side.
Camera equipment i used, Nikon 3Ds with tamron macro sp90mm Di and a tripod.
Over the weekend, I will go away to Edinburgh (Scotland), so images from there next week.