Square Chamber Oil and Water Toy

Oil and colored water in an enclosed volume. The system has some interesting dynamics:

http://www.youtube.com/watch?v=qKU1z01YzcA

The OpenSCAD file is parametric, so you can experiment to change the flow parameters. The default parameters make the flow somewhat slow, so you could try to make bigger chambers/channels if your printer bridging performance is good enough. If someone knows of another safe immiscible fluid combination that is less viscous, I would be enjoy being told about it