Thanks Daryl, you are welcome mate.

The rubber comes from a broken dam kind of thing, that the Forestry Dept used on Mt Pickapene's steep tracks, to divert the water. They used it instead of having a machine make Wooboys, or angled humps across the track. When you drove over it, it just flexed over and sprung up again. A Ranger, on his own, could place them easily with just a hammer and long nails, driven through the piece of timber they were attached to.
I collected some broken pieces, from there, when I was working in the Fire spotting tower on the top of the mountain. Lovely views, but scary when a strong 100kph wind was blowing.

I've used the rubber to make non-slip butt pads as well.