A few years ago , one of my daughters wanted to play around with my camera. She had seen some shots like these online and wanted to figure out how to do it. We played around with it for a few hours until we figured out how it is done. Some of the people that are doing these make some specialized shutter triggers and fancy setups, Ours was pretty simple, a glass bowl, water, food coloring and an eye dropper. Camera was on a tripod set at as fast of shutter speed as we could get with the light we had.We tried different food colorings, milk,etc for different effects… Had a lot of fun, spent some valuable time with my daughter and ended up with some fun shots.