This is my wife's plastic watering can. The original sprinkler head cracked and fell off. I replaced it with standard PVC parts from the local hardware store.
Why bother? Most watering cans I found on-line were metal with prices ranging from $25 to $50 each. I made my sprinkler head for about $3.50.
Step 1: Parts Needed
The red numbers identify each part. Number 1 is a 1/2 inch male adapter. Number 2 is 2 x 1/2 inch bushing. Number 3 is a 2 inch slip cap. The slip cap has been drilled by me to make sprinkler holes for the water streams. The slip cap slides over the bushing and makes a fairly tight fit by itself. You could glue it, but leaving it without glue allows you to remove it later.
Step 2: Fitting the Male Adapter
I intended to make photos of each step, but became so engrossed in the mechanics of making my sprinkler head work that I forgot to take the pictures.
The factory threads on the watering can spout were 3/4 inch in diameter. The male adapter slid over them with a close fit. I drilled a hole about 3/16 inch in diameter through the sides of the male adapter. Hot glue fills these holes to lock the male adapter on the threads. I coated the threads on the water can with hot glue and quickly slipped the male adapter over the threads. I also pressed some hot glue into the two holes I drilled. The hot glue makes a good seal and very firmly secures the male adapter on the watering can spout.
Step 3: Finishing the Can
Drill about 20 holes 1/16 inch in diameter in the slip cap. Spread them out evenly. (Check each hole and clean away any burrs that restrict water flow.) This will make a good shower effect when the water pours. My mistake was that I made too many holes spaced too closely to one another. That gave me a large dribble rather than a gentle shower. I had to close some of the holes with hot glue.
Screw the bushing onto the male adapter. After drilling holes in the slip cap slide it onto the bushing.
Step 4: The Shower of Water
Here you can see how the head makes a gentle shower of water streams. For test purposes I am pouring water into the kitchen sink.
Step 5: A Problem?
The inside of the bushing holds some water. (I added coloring to the retained water so it is more easily seen in this photo.) Even more water is retained initially, but some has dripped out. A puddle about 3 inches in diameter forms under the new sprinkler head. If you only use and store your watering can outdoors, this is likely no problem for you. But, if you want the extra water to go away, you could drill a weep hole where you see the black dot and the retained water would be gone before you finished walking to your storage shed.