I believe Starboard would probably be the way to go for the dash panel. West marine carries it but you should be able to do better online.
Like guys have said, starboard is the way to go. Lasts forever, easy to work with, and available in many colors. Best place online I found is at:http://www.buckwoodcraft.com/king_starboard.htm Good prices and shipping is real quick. They'll cut to whatever size you need.I did my dash a few years ago and its holding up well, seeing many hours of direct sunlight every year. Not the best of jobs, but works fine. If I could do it again, I would use a router bit to put a nice edge on the trim. Your possibilities are endless as far as guage/ electronics placement. Good luck with the project.
Know Before You GoLocal Weather | Marine Bouy Weather | Inshore Forecast | Offshore Forecast | Interactive Wind Charts | Tide Charts | Sea Surface Temps | Chlorophyll Concentrates | Online Chart Viewer