Hiya All,
Something I noticed earlier when I was patching a flat roof with heavy duty 'green' roofing felt. If you hold the felt up and brush it gently with a metal wallpaper stripper thingy, lots of small, fairly sharp bits of grit fall off. I think they'd make a fairly good representation of ballast on a railway track dio or similar. Or the sharp rocks in a desert dio.
hope I've helped someone, somewhere.
Tom

Hi Tom

I'm not quite sure, what roofing felt is. Do you have a picture of the felt and of the sharp bits that fell of?

Good and useful ideas are allways welcome.

Jesper,
Here in the UK its a roll of rubber like material that's used to cover a roof that has no pitch (angle) to it and is not covered by tiles or shingles. You sort of nail/glue/tar it to the roof boards to make them more weatherproof. It comes in various thicknesses but the type I used is about 3mm thick, comes in rolls of 10x1m and has a grit coating on the top surface. It's seen everywhere over here from shed roofs to some houses.
Tom

Now, I know what it is. We have it here as well.
I think there is a spare roll, at my mothers summercottage. I'll give it a try, next time I visit.
Thanks Tom