For gallon plastic containers with a 36mm outside diameter opening. There are two spout sizes to choose from.
Spout cap existing:
Cut a 25mm hole in the cap. I used a 1" hole saw to create a nice circle & finish up with a knife. Use the gasket if there is leakage. Can also use silicone between the spout and cap.
Spout cap printed:
Printed with 0.3mm layers. Last part looks better if printed slower. Clean inside ridge with rotary file and rotary wire brush if necessary.
Printed with 0.3mm layers. Cleaned inside with round file and outside with sandpaper at the spout end. Use slower speeds at the end of the print if things start to look ugly.
Spout remix: http://www.thingiverse.com/thing:969219
Container cap remix: http://www.thingiverse.com/thing:65922