I made this contraption to allow me to slowly water plants without having to spray or drip water on the surface. It acts as a delayed watering system, it dispenses water below the soil surface directly(or closer at any rate) to the roots of the plants, reducing water loss from evaporation and drainage.

The flow rate is now controlled by 5 flow restriction inserts that can be modified and printed separately from of the spike cap to allow me play with/ adjust the flow rate without having to reprint the entire thing each time.

I also created a printable bottle so I would have a 'marginally' less unsightly bottle compared to the 'Simply' brand of juice bottle I was using before. It holds just over 1 liter.

My Print Settings/Suggestions: (Your mileage may vary) 

• Printed at 0.12 mm layer height 
  • The small 0.015" holes may not print if your layers are too thick.
•  0.04 mm nozzle
• Print with spikes facing upward (no supports required)  
• I printed in both matte PLA and black ABS
  • ABS is obviously the strongest, but PLA works fine
• I printed the cap seal in black TPU (not sure what hardness) 
  • 0.08-0.12 mm layer thickness 
  • Cap seal is not strictly necessary if your print quality is good. About half of my prints were leak free without the seal 
  • With or without the cap seal, the cap may leak if print quality is too low. 

Bottle Reservoir:

• The cap is originally modeled to fit the threads of the ‘Simply’ brand of juice bottle but cap threads are normally fairly standered and other wide mouth containers may work as well.
• For correct operation you must poke/drill/gouge/chew,  a small hole in the base of the bottle to allow it to equalize pressure.