A.M.
We used metal gates too and that was a concern for us. We got lightweight bumpers and tied them on the inside of the gates while our daughter was playing in the "yard". When we were all done we would untie the bumpers and put them out of reach. It was a bit of a hassle but worth it to know that there was something soft between her head and the metal. Also look at the foam strips that you can get for table edges. It soft and you can cut it to fit the balls of the gates.