It's a championship quality snooker baize sprayed with yellow paint.
I somehow managed to get it for free from Hainsworths (the mill that makes baizes for the tables used in the professional snooker championships) for a convention game, way back when. They even delivered it free of charge: I know someone there.
It's 97% tightly woven, pre-shrunk merino wool, so it doesn't stretch, even after being laid over hill shapes for weeks. It's too good for what I'm using it for and it's worth about £700.00 GBP.
It's so well made and so densely woven that, even after ten years of spraying and respraying as the paint wears off, if you turn it over it is pristine green and looks like new.
I LOVE IT!!!!!
BTW, the contours were edited to the photo using MS Paint, they aren't actually drawn on the cloth.