EU bottle Tornado / vortex / hour glass coupler

I wanted a water tornado/vortex cupler for PET bottles with EU size and use it aswell for dry content. I took the cap design from  https://makerworld.com/en/models/1455210-water-tight-eu-plastic-bottle-cap-pco-1881?from=search#profileId-1516510 and changed it for my purpose.

The outer straight faces make it easy to use a wrench if you can unscrew by hand (and not strangle the bottles). It give the opportunity to print it vertically, but I got mixed results. 

I wanted to use it to fill bottles with dry content (e.g. sand, small colorful beads) and then all sizes and filaments work fine - no leaking. 

So I created several hole sizes:

• Full hole → good for big bottles and water tornados and does not leak for me with TPU with AMS*
• 12.5mm hole → for smaller but longer lasting tornados on big bottles → good for medium bottles (leaks for me use outside)
• 10mm hole → good for small bottles to have some uptime on tornados → good for fast action with dry sand in small bottle
• 7.5mm hole → good for dry content in small bottles with good speed but more uptime → my favorite for sand
• 5mm hole → if you want a real long lasting time → nothing for small kids :-D

*If printed with TPU for AMS it works really well and does not leak for me when filled with water. After many times screw and unscrew it starts leaking for me. 

Screw it to tight and and breaks for me. If printed in PLA all sizes leak for when filled with water. Printing it vertically works somewhat for me with TPU.

• Print on hole side
• with support → come off clean
• vertically mixed bag
• sliced either way not nice
• took the profile from the designer of the cab and modified it to add support

I cant get it right when holes are limited to keep it leak free, but it does a good enough job for Junior → use it outside with water. Dry content works perfectly fine and my junior is more interested in the dry stuff. He is loving turning it over and over and over again.

FYI: I removed the cap and plastic ring for all my bottles.

I may want to add a holder to mount it to a IKEA Skadis board. I am still working on that. 

If somebody can tell me what would help make all sizes water proof it would be nice.

Dry Content:

My wife but orange colored decoration sand with a scent - dont do that. Better get clean fine sand - maybe dry it to kill everything we dont want - its the better choice. If the bottle breaks it should be something children can consume - who has not his fair share of send consumed?

Small colorful beads would be nice too.

Wet or dry content dont let you kid alone with it - their ultimate potential for destruction can not be measured. 

Update: 08.08.20205

I added a holder for the Ikea Skadis board so the a hourglass made from 2 0.5 PET bottles can be mounted: https://makerworld.com/en/models/1679676-activity-board-hourglass-ikea-skadis-mount#profileId-1779272