Real hockey and roller hockey rink boards are made of a polyethylene sheet good known as "marine board" or "sea board". It's just a U.V. stabilized PE product, so it doesn't rot in the sun. You could buy a relatively thin sheet of it and put it over plywood boards to get a little more bounce, or you could buy thicker material and use it as the board itself.
St Louis roller hockey rinks use both systems. They play the same as far as I can tell. In my experience, having the right ball for the ambient temperature makes more difference on the rebound than wood vs plastic boards.
Chicago Bike Polo 2003-2008
St Louis Bike Polo 2008-now





















I love the boards. Ours were taken down (city bylaw thing), so it's back to the wire fence. It dampens the ball and sometimes even wedges it underneath the gnarled trimming, and the poles being on the inside sometimes meet with my shoulder but it's just a matter of getting used to it. I feel spoiled when there's boards.