Hmm… what about pendulum painting? Where you put paint in a bucket, put a hole in it, and let it swing back and forth over the canvas?
On one side he chooses paint and size of hole and initial path and so on, but on the other hand he let nature and physics do the actual painting for him.
If I buy a bread at the bakery, ham and cheese in the grocery store, and make me a sandwich, who’s the creator?