My glass is your glass.
I've seen some furniture made where they buttered wood with mortar and waxed it to look like a heavier stone piece.
They attached a mesh first so it was all block forms.
I saw some stone molds on eBay that I was considering using to make a stone face for my fireplace and hearth. It's painted brick now. I thought about casting enough to cobblestone my driveway, but I'm sure that's a bit ambitious.