Single-print garden hose spray nozzle with trigger to control water flow. I built it as a proof of concept prototype. It works as intended, but it does leak somewhat due to the lack of any rubber gaskets. (However, most of the leaking can be eliminated with proper print settings. See print notes below for important info on printing strategies to minimize leaking.)

Fits a North American (US/Canada) standard home garden hose thread. Be careful when attaching your hose as it's somewhat easy to cross-thread.

The spray trigger has no spring and uses water pressure to generate resistance. Consequently the button will be loose until you turn on the water. (Make sure you work the button loose after printing -- it shouldn't be too hard as I left the tolerances a little looser than necessary.)

Note it's designed to be printed with the nozzle end face down on the print bed, so make sure you rotate the STL file accordingly. Use supports (external only) to hold the handle and trigger button in the proper position during printing. No internal supports are necessary.

The handle size is a little smaller than ideal for a full grown adult's hand. I did this to save filament since it was just intended as a proof-of-concept prototype. The trigger travel distance is also less than ideal for easily controlled intermediate flow settings... it is more of an "off" or "on" button. A bigger mechanism would have improved this but would have required more filament.

Based on this experiment, I suspect it would be relatively easy to design a full size garden sprayer that works pretty well. A more practical design might also have selectable spray nozzles.