Poly board from H.D

[spareparts]

PVC board? Compares to "Star Light Board"

[SkunkBoat]

The pvc board is a lot lighter than Starboard (High density polyethylene).
There is a brand name AZEK that is $$$ but HD has a cheaper version also.

It cuts like wood. Comes in trim board sizes also. It is "foamy" so the edges are rough and exposed edges tend to hold dirt. The faces are smooth and hard. It would be a good flat surface for a dashboard, but you would have to put trim around the edges.

I used it as backing for my bolsters. Perfect for that. Used it for trim on my house too. You could build a door. Not sure if it would hold up as a deck hatch.

I wouldn't use it for a cutting board.