I am the original author but I'm new to printables, originally I uploaded to Thingiverse. 
The plastic rose for my watering can broke, I figured there would be a replacement part here but there was only one for the whole head not just the sprinkler part, so I drew one up in Tinkercad.

This replaces a rose of 85mm diameter. Scale to your watering can's dimensions.

I've included one with the holes and one without if you prefer to drill your own, my placement was very vibes based but works well. They could be optimised if you were able to drill conical holes.

The piece should just snap on if you have the right kind of can but you could plastic weld /glue if you prefer.

I printed upside down with supports in the end as with the holes it struggled, but I reckon a well dialled in machine could handle printing as is. Let me know how you get on.