Finding the right roofing slates

[epatrickt]

Our house has a few roof sections and in their infinite wisdom, over the years, various builders have gone for slightly different sizes. Our lovely neighbours have used an air-rifle to shoot holes in some of them and so we need to get a small number to replace them. They're not standard sizes that the local builders' merchants keep. Any good ideas where to get them identified (blue/other, man-made/natural etc)?

The 2 sizes are approximately:
10x20.5"
c11"x22"

The screenshot is one that was lying about but looks like the ones installed.

Thanks!

Patrick

 

[jeds]

ebay or local reclamation yard would be your best bet, calling into the local gun shop on the way home.