Corrugated Roofing
all available as:

3- 2"x8" long strips - use for 8' sheets- - $5.00

OR

3 - 2.5"x8"long strips - use for 10' sheets - $6.00

Aluminum

All the sheets on the left in this picture show the the material as it comes. The others show varying degrees of weathering To use PanPastels on aluminum it needs to be primered OR as I prefer, brush on a coat of clear Gesso.

Corrugated Silver Card Stock 

I swear this looks more like metal, than metal. This material is the best I have found for simulating a roof surface that is just beginning to show surface rust AND none of those annoying little silver specks that you get with aluminum.

Steel Gray Card Stock
This is a new material I am trying. What makes this particularly useful is, it's made specifically to be used with PanPastels. Look at the second row how easily it took a simple application of PanPastel Silver followed by various rust application. The rotted sheets were done using a heat gun. Great stuff to work with.

Galvanized Gray Card Stock 

This is another new material that has a very natural galvanized look to it. Also made specifically to be used with PanPastels. Really easy and fun to work with. 

Rusty Brown Gray Card Stock 

If you want to start with a dark rusty color, then this is the one. As you can see it takes PanPastels wonderfully. Note, the second picture with the silver application.