The product we use is called Redi-Shelf made by
Roseburg Forest Products. We have also used Missoula
Particleboard "White Shelving 3/4", 23 1/4", x 72".
You can see the Redi Shelf by clicking here.
Check with your local lumber yards, etc to see if any
of them carry it. We get ours at Menards and Fleet Farm
(both midwest chains, I'm afraid).

If all else fails, you can rip a sheet of
plywood in half lengthwise. It will yield enough for
2 boards.

Thanks, so much, for trying my pattern. You will LOVE
your board. My husband has been making them for lots
of my friends in my area.