Printables link. Apologies for the... very lazy select + background blur. In the land of windows I would have used paint.net, but I'm coming to you from a mac today and haven't found a great alternative.

Gravity bong?

https://opengraphica.com/

this in-browser photo editor works for me for basic stuff in firefox

I loled. It's a tornado adapter for a pair of Gatorade bottles. These were pretty popular when I was the age my kids are now, granted they were for 2L soda bottles.

Sorry to burst your bubble but these have been a thing since at least the 90s:

https://www.amazon.com/NANAOUS-Tornado-Bottle-Connectors-Cyclone/dp/B08HCWKM18

But if you mean "designed" as in "I didn't create the concept but I made this ground up in Blender or whatever" then hell yeah, that's awesome!

Sorry to burst your bubble but these have been a thing since at least the 90s

Oh, I know. I was a child in this era and wanted something similar for my kids.

I just wanted something that could attach to a more sturdy bottle as 2L soda bottles are... pretty flimsy when a kid is shaking them around to get a vortex to start.

Right. I've been out of school too long lol

Finally, breaking down the bottle gender barrier.

Prints are porous and will leak eventually. It'll start sweating or dripping eventually.

https://www.photopea.com/ is a faithful browser based Photoshop clone

I had one of these years ago, and they usually start to leak after a while regardless. It doesn't provide a good enough seal with disposable bottles, and swinging it back and forth seemed to wear it out over time.

How does this one compare? I remember the 2L ones.

Now I'm curious how the tornado changes with different size / shape bottles

Even ABS?

Even anything. Resin is probably safe. Water gets through the gaps in the plastic after it cools. Bacteria and mold can take root too

figuring out threading is hard - how'd you do it?

thinking of some similar projects...

Eh. I've had good luck with PETG, which won't break down in contact with water. It helps to print three or four walls, and some simple post processing really seals the deal (ha! sorry for the word play).

For this particular project, finding a model that already had the threads in it.

More broadly, threads usually follow one of a handful of standards. It's just a matter of figuring out which standard is being used and then finding the size. I haven't found a great way of approaching that for bigger threads, beyond measure with a pair of calipers, but if you're working on nuts and bolts a metal fixture with various threads is the way to go IMO.

So, an hourglass using water instead of sand? /s

It workes pretty well. Most of the injection molded vortex generators have an oreface that restricts flow, so I incorporated that concept into this design.

The only downside is fluid capacity.

This is true, but also not a huge deal for this design. Store it upright and water isn't contacting the print. While in use there's not much prolonged contact, or even contact area, between the water and the print.

These weren't absolutely leak free, but they didn't leak any more than the injection molded pices for 2L bottles.

An o-ring would probably fix it right up.

Looks like one of those tornado tube things you could get at Natural Wonders back in the day. Half fill a bottle with water, screw on the tube, then screw an empty bottle onto the other end of the tube. Then turn the assembly upside down and shake it around to produce a vortex in the draining water.

That's exactly what this is based on.