The longer I am, the better the experience. What am I?

Usually seen in parks Popular with kids In verb form, it just moves like a pendulum

Built to break what can’t be killed, I face the rage, you feel the still. Neither sea nor land I stand, A fist of stone with open hand.

First word: big eyed, grey and green. With the long key in between. Last word: cut and glue together, make a paper stream.

Replaced by a ring, in the past I’d glow and sing. The alternate to fist and wood since low volt was made a thing. My first four takes a swing, while my last four yell a ‘ding’. I wonder who that is? Is it a ditcher? -Donnnnggg- -Dinnnnggg-