While researching a solution for my ultrasonic rangefinder, I came across "expanded PVC" for use as a snow board. I relegated the "old" wood one for the rangefinder and I am using the new one for CoCoRaHS.
I bought a 24" x 24" x ¾" white expanded PVC sheet from Interstate Plastics. (PVCWX-PVC Expanded Sheet - White
(0.748 x 24 x 24)) I bought the thicker one, since it was only a few dollars more and is quite "beefy" looking.
From what I have read, expanded PVC sheet is what NWS uses for their snowboards. I like it since I am no longer scraping up white paint flecks when I take my cores.
Greg H.