This is a high flow venturi injector for a cold plunge (or whatever other use you can find for it). It's designed to fit in a 3/4" PVC slip fitting and 1/4" tubing barb. 

People typically hook up an ozone generator as a sterilization method to keep cold plunges clean and that's why I designed this. Some ozone generators have a pump incorporated to push the ozone through an airstone bubbler, while others don't have the pump and require a venturi to pull the ozone into the water. This injector can be hooked up to either type of ozone generator. 

The ID of this venturi injector is larger than a similarly sized venturi, to accommodate the higher flow of pumps typically used in cold plunges. I currently have it hooked up to a 1200 gph pump. I printed in PLA because that's what I have on hand, but that probably won't hold up to long-term ozone exposure. 

Full disclosure: Use this at your own risk. Anything that reduces the output of a pump adds stress and could potentially shorten its lifespan. I've only had it hooked up for a few days and it seems to be working fine, but I can't comment on the long-term results. Similarly, you'll probably want to print this in a material that's resistant to ozone degradation (the internet says that's ABS but I'm not a materials engineer).