I had some extra marine grade three quarter plywood left over. I used that to make a 12 inch square 3 layers thick. Coated it with spar varnish and have excellent results using them with a 17K 5th wheel. Only problem is there heavy. Most truck camper rigs have weight concerns so in that case I say go with the plastic ones available at Camping World. While your at it, join there club so you can get there discounts, your savings will more than make up for subscriptions cost. Just in case you don’t have a weight issue and you like to build things like me take a look at plywood costs before making your final decision.