I designed this to mix a small amount of liquid fertilizer into a stream of water from a garden hose. I have a worm composter that produces quite a bit of liquid fertilizer and I wanted to dilute it and sprinkle it on my lawn.Print it out. Break out the little support cylinder in the bottom and cut out the think membrane over the hole.Place a rubber washer in the female threaded end. Tap the vacuum port with a 1/8 NPT tap (don't force it and crack the plastic) The hole is already tapered so hopefully it shouldn't be too much work to tap it. Insert whatever 1/8" npt fitting you want into the port (JG fittings are nice)Hook it up inline with your sprinkler or whatever.4/16/16 I just ran the original venturi through netfabb to fix some problems. Hopefully it is good not. Made a slightly different stl (called venturi 3.5) that should have slightly looser threads and has no built-in support material. I also ran this file through netfabb.