I finally finished another batch of rocks...
I think I'll have more luck if I just paint a design on the rocks, as opposed to seeing what their shape reminds me of, and then trying to paint a recognizable object onto them.
The ladybugs are the smoothest rocks I've found yet, but I had to paint them multiple times because each time the paint dried, it wanted to stick to everything but the rock. Unfortunately, I didn't get them done in time for the latest hunt. The hunters took a picture of all the rocks they found, and none of my first batch were included. Apparently, I hide my rocks really well. Some people took pictures of rocks they found in the places where they found them, and I'm realizing that they are basically leaving them out in the open for someone to stumble upon as opposed to hiding them under a pile of unpainted rocks or underneath a bush. Now that the temps are rising, the snakes are out, so I'll re-hide my first batch in less risky locations whenever I can get out to plant the second batch.