Rubber liners for fiberglass fenders?

[PcarPhil]

My widebody longhood project continues to move along (now with a different chassis). I'm planning on using fiberglass front fenders but I'm concerned about rocks being thrown from the tires and cracking the fiberglass.

It's been suggested to use a fairly thick rubber liner glued to the insides of the fenders to help minimize rock damage.

So now I'm starting to wonder where I can get some rubber material for this purpose. I'm thinking something like 1/8" - 3/16" thick would work well. Perhaps purchased in a roll or 4x8' sheets.

Any suggestions on where to find some suitable and inexpensive material?

Thanks for the help.

[Axiom]

When I use fiberglass fender I spray Wurth sprayable sealer under them. I spray as thick I am asked to, so far it has work well, it is about 16.00 a can.