Tesla valve bathtub toy

A bathtub game for children (or adults) who like to experiment.
The toy is based on the Tesla valve, an asymmetric tube.

Here is a small description:
https://www.lesics.com/how-tesla-valve-works.html

All you need is a syringe and you're ready to experiment. 

Which direction does the water flow more easily?

Printing tips:
Print at as high a resolution as possible so that the luer cone is round enough for the syringe connection.
If you print from transparent filament, the path of the liquid is clearly visible.