Thanks guys. I've only seen one source that sells these. The ones they have a all kidney shaped and do not, IMO, look at all natural. I can draw pretty well, write up plans and schematics well also, but my "handiness factor" stops at simple home repairs and reef aquarium plumbing. I guess, worst comes to worst, I would rather get a natural piece of rock and sculpt it myself than create someting out of mortar, fiberglass, etc. A project like that is probably beyond my talents. Lava or tufa rock would be easy, since they're readily available, even drilled, at aquarium shops, but I'm looking more for something like granite or that "blue stone"/flagstone they use a lot in the north east for ponds. I suppose I could steal a stone from my father-in-law's pond (least he can do since I built it, after all). I guess I was just looking for the easy way out.
Anyone know what type of stone I'm talking about? How to grind a slight depression in it and drill holes?