Closed tube containing dyed water arranged into an interesting shape. Before I built it I imagined it would look like four leaf clover, but once it was built my brother asked if it was a butterfly so I guess that's what it is. It is very simple to build. I imagine if you can drill holes reasonably accurately you could make the junction piece out of wood or foam. The scad is parametric w/ respect to wall thickness and hole size.
Here is a video that shows the flow behavior: