This is a Laminar Flow Nozzle design I came up with in 2020. It's the MkIII because it was the third one I designed. The other two haven't been released anywhere. It's relatively small for a Laminar nozzle, and doesn't behave perfectly, but I learned a lot making it, and I think with a decent pump, low-pass-filter, and good exit point on the nozzle, you can get a decent laminar flow out of it. This one is designed for a ¾" hose.

It assembles together with M3 threaded rod (About 150mm in length) and uses 62mm diameter O-rings (60mm ID, 64mm OD, 2mm thickness). The middle section, titled the "straws" section is meant to be printed at ~30% infill to produce small diameter straws that the water will flow through. You can mess with the shells in your slicer to produce the appropriate spacing. The 3d printed exit aperture  will probably not result in a clean stream. I experimented with cutting and sanding a piece of aluminum from a soda can and that worked out okay. On my next version I think I'd just start with a large metal washer.

Between the Entry cap (the bottom) and the Straws section you will need a few layers of scouring pad, that serve to reduce turbulence in the water.  

The cutter is actuated by a rotary solenoid - the mounting included is for a Lucas LEDEX H-2346-D32. You can find them for pretty cheap on eBay used. I don't know how water resistant these are, so be aware of that.

Included are the files in both STL and STEP formats. The former so you can print, the latter so you can... alter, I guess. I don't know a ton about STEP, but I know it's good portability for CAD designs.

If you print it, use it, have questions about it, I'd be delighted to talk to you. You can find more information about my design and development process on my website.