Resting a fish tank on its side, I placed a shallow oven baking dish on top and filled it with a couple of inches of water, to which I slowly added olive oil (extra virgin as it happens, as that was what I had to hand, but I am pretty sure any oil would do) using a small syringe. One drop at a time, I carefully made sure that the oil blobs were of different sizes and not too close together.
On the bottom shelf of the fish tank (as one of the sides had now become), I put a colourful piece of paper that I had created in Photoshop.
To one side of the tank I had a large lightbox (leftover from the days of slide viewing), on another side an LED light and on the third closed side an off-camera flash firing into the light box. The fourth side, the open side of the fish tank, was my camera and tripod, of course, as well as access to changing the coloured paper.
Experimenting with different heights between the top dish and the paper (using books to lift the paper if necessary), I was able to see what effect it had on the patterns reflected in the bubbles.
As I played around with the camera settings, I discovered that different apertures created very different effects.
I had every intention of photographing my set-up, but I got a bit carried away with looking at the pictures I had taken, and by the time I got round to it, my very kind LSH had already disassembled the equipment for me.
It was a lot of fun and created some amazing abstract and arty images.