I remember reading about an answer machine that would kind of 'lay' a small ball every time a message was left.

You'll be able to tell if you had a message by visually scanning for one or more ball.

To listen to a message, you'd take a ball and place it at a certain position to execute playback.

I found the coming together of physical and digital in this way, incredibly alluring; and still do today.

The article's focus reminded me of similar outcomes.