Thanks John that is kinda where I am at, I cut some out of the same stuff I made the door panels with, which is a heavy card board pressed paper wood something. The original stuff at the door edge is like tar paper pressed board about a ÂĽ inch thick which would repel water. I liked that because we get sooooo much rain here and that area is at a water shed point.
I went up to HD and they had some synthetic flooring ÂĽ thick that would have been water proof, but I needed to buy a whole package plus there was not enough room to make the full arc because it was not wide enough. I am going try and paint the pressed board, but I doubt the paint will stick well maybe a stain would work better.
Making my own interior saved me some money, but it was a non-cost effective way and it taking more time than I thought. I saved a lot on the door panels, but the carpet was probably wash even at material cost without labor.
steve