A pythagorean cup is similar to a regular cup, with the exception that if you fill above a certain height inside the cup, then all of the contents of the cup will be emptied.

This is good to teach people not to be greedy ;)

It works by having a hole at the bottom of the cup, that goes up through the center part of the cup and back down to inside the cup. Once the liquid passes a certain point, gravity pulls the liquid out and the concept of "Communicating Vessels" makes sure to empty the whole cup out.

You can read more about this cup here: [https://en.wikipedia.org/wiki/Pythagorean_cup](https://en.wikipedia.org/wiki/Pythagorean_cup)

I ran into this randomly one day and thought it would be a nice project to create with my printer.

I modelled it in Fusion360. There are two versions of it, one with a handle and one without. Since I wasn't going to actually use it, I printed the version without the handle for simplicity, but I added a nice coffee-mug-like handle. If you print the version with the handle you'll probably need supports.
The version I printed without the handle works just as described. The version with the handle is the same exact model, so should work too.

NOTE: I do not recommend actually drinking from the cup, unless you know the material you printed it from is clean and safe for drinking out of!

Print instructions

I printed this with PLA (from Hatchbox) with 0.2mm layer height.
Took about 8 hours and works nicely.

The version without the handle doesn't need any supports.
If you want to print the handle, you might need to add supports under the handle.