I now make the planks out of extension ladders. Buy a medium grade extension ladder and slide the two sections apart. This will give you two planks if you cover the sections with half inch plywood. I use self tapping roofing screws to fasten the plywood onto the ladder sections. It makes nice light planks 24 inches wide. You can make double wide planks by laying the two sections side by side. A piece of half inch pipe can be slid through the rungs of the two section, near the middle, to take the bounce out of the assembly and to distribute the weight when someone walks along one side.