I have used a piece of channel iron, either 4" or 6", to make a bumper- - - -make a series of pie wedge shaped cuts in the ends, and use a hydraulic press to make radiused ends. Then weld the cuts back together and use an angle grinder to form the ends into a smooth semi-circle. It's a bit labor-intensive, but the end product looks good, and it's tougher than woodpecker lips. You can make a top plate from 1/8" steel sheet if you want something fancier than a simple piece of channel iron.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!