I found a solution by playing with the aha tool, I warn I'm just a beginner.

What you need to do is go to your rounded shape that you want to use. Then you right click, and convert to curve!

Then you can use it with the eye dropper!

Hope it helped you ;)

What you need to do is go to your rounded shape that you want to use. Then you right click, and convert to curve.

Then you can use it with the eye dropper.