Third attempt at designing a 3D printable Pythagorean cup (i.e., self starting siphon) in Fusion 360, for layering fluids of different densities by injecting a denser fluid under a less dense fluid. With the eventual goal of using such a siphon to make a Black and Tan.
More details at https://blog.doingsciencetostuff.com/2019/10/13/beer-siphon-mk-3/ .
When I printed this, it was very fragile and attempts to repair it rendered it nonfunctional. To save on print time and support material, the test print was printed upside-down. I believe the design is sound, but your mileage may vary.