I tapped out messages on a hollow tree with a rock after trees became available and got hollow. It was much better than tapping out a message on a big rock with a small rock. Both methods were wireless and free of charge.
I never told you before, but I hollowed out that tree for you.
Was gonna make a canoe but I thought, “You know, it would be really nice of me to let CG have this to use as a communication device.”