I had a very cheap watering can that the white water spout broke off very soon after purchasing. Several years later the wife asked me whether we should throw it out, but I decided to make a replacement part on my 3d printer.

I used the ISOThread.scad library https://www.thingiverse.com/thing:2158656 but I modified it a little bit. Mostly because I was not using ISO standard threads.

I found it very difficult to get the thread to match. There are some settings in the file for printing out just the nut to test the threads, but I also included an option to print out half of a nut so you can look inside and decide what the problem is when it doesn't work.

I recommend that you play with the print settings because this has to be waterproof, and I have found that most of my prints are not water proof, water leaks through them like a sieve!

I printed with 4 shells and 40% infill, with a few percent of over extruding,I was thinking of doing 100% infill.
I still had a little problem getting the first layer to look nice, but I am not going to print it again.

I used 0.2 height, PLA.