This Orbit sprinkler has a heart-shaped cam driven by (I presume) an impeller inside the sprinkler body. the cam drives an L shaped connector with two studs on the ends. The connector then saves the bar back and forth, which controls the direction of the spraying water.
My sister gave me the sprinkler when one of the studs had worn off. I took a few tries to get the tollerances just right, but I got it. Interesting to note that the original piece could have had much tougher studs but the designers chose not to. Design for failure?
I flipped the model over before printing.
I also made sure to print out a 1:1 drawing and compare it to the original part to check that my caliper measurements were OK. Still took three prints to get it right! Those are some tight tolerances.